Question for the pros...

Seems to me that both factory ammo and loading data for the 7mm Rem Mag is a bit on the anemic side. Is this intentional? I found data dating back to the 70s and early 80s showing data for 160r bullets allegedly choreographed at 3100fps in production guns and 175s at 3000 fps.

IIRC wasn't the cartridge originally designed to push a 175gr at 3050fps?

I know I've pushed 160gr acubonds over 3000fps in my 24 inch 700 with zero pressure signs. What gives?

3308

Yep, been going on a while now. I have Hornady Vol II and most newer manuals don't touch it.
I've loaded 162s at 3160 and didn't blow up anything EVEN a case. imagine that !!

I'm not a pro, so I'll not try to answer your ??


Jerry

Pressure isn't constant shot to shot. Modern testing equipment is able to show that the probability distribution of the pressure for the 7mm Rem Mag is spread out somewhat more than other cartridges. So the loading was changed to lower the mean pressure of the distribution enough so the area in the no go portion of the high pressure tail of the distribution became acceptably small.

Okay -

Many loads today 'hardly' beat the 270 Win velocity with "proportionate" bullets. That's my beef.!!


Jerry

here is the true answer LIABILITY no body wants to end up in court,over a rifle that blew up anymore so all ammo manufactures and books on hand loading have reduced the amount of powder used for their own law suit protection and i can understand why. my old hunting partner work for a ammo manufacture for 40 years and he spent plenty time in court and trying to solve problems from a rifle or pistol that had problems,most problems were from a hand loader using to much powder. that`s why velocities these days are lower > less powder,less pressure,less lawsuits its always about the money

I'm sorry, but I can't resist:

I want to see those choreographed bullets dance.

Ploughman; at 3100 fps, they are choreographing too fast for you to see 'em

Mine isn't.

Reloader 26 is the answer to all questions 7mm Remington Magnum with heavier bullets.
John

Id love some good data on the 160s and 175s. Ive had old timers tell me that the initial goal with the cartridge was to get the 175s over 3k...and they were able to do it roughly matching a wildcat that Warren Page was slaughtering animals with all over the world in the smaller RM case. I shoot and load for a couple of 270s and I agree 100% that with MODERN data...they have turned the 7rm into a 270 or 280. Not that thats bad company to be in...but with the bigger tank you should be able to smoke them.

Or retumbo, h1000,7977,8133

Mine isn’t either.

RL-26 is good stuff.

DF

Spot on.

Not worth the hassle...

Easier to just put him on ignore!

I finally got some 7977 and 8133 on hand. Looking forward to seeing if they'll perform as advertised.

Mule Deer has a very good history of the 7mm Rem Mag in the Gun Gack book. Happy Trails

Ok...just ordered the book. Ive been meaning to anyways...made for a good excuse

Ploughman
Most likely performing THE FIREBIRD.
Great choreography.

Several reasons the 7mm RM is "underloaded," aside from the primary reason posted by Mathman, widely varying pressures:

The original factory loads were chronographed in 26" barrels, common back in 1962 when it was introduced, with a powder then unavailable to handloaders, IMR7828--which even today performs alongside newer magic powders.

This allowed the advertised factory velocities, but even then Remington factory ammo didn't quite make them, according to the Speer #6 manual, which contains a section on chronographed factory loads.

Also, the early reputation of the 7mm RM may not have been established because of actual ballistics. A lot of hunters and handloaders back then didn't have chronographs, so accepted the published factory and handloading velocities, yet their rifles still killed game with "reduced" ballistics.

A good friend bought one way back when, when everybody here in Montana had to have a "Big Seven," and according to the loading manuals his 160-grain handloads got over 3000 fps. It knocked the snot out of everything from deer to black bear to elk.

He bought a chronograph a few years later, long before most people did, and found out his magic handload got around 2700 fps, pretty much warmly-loaded 7x57 velocities.

But then, the 7x57 has been knocking the snot out of big game for a long time now!

You wouldn’t think that the physics involved with the pressure-spread of the 7 mm RM would be all that much different from, say, the 7mm Wby, which cooks the 175 along to 3k pretty easily. Is it the singular and famed radiused shoulder of the Wby?

I remember my first purchased lie-detector tried out on my favorite, hot-shot 140-gr, 270 load which thought to be about at the speed of light meandered along at about 2700 fps.

It’s interesting how much perception feeds into confidence or the lack thereof.

George,

The radiused shoulder of the 7mm Weatherby doesn't have anything to do with its comparatively consistent pressures. Instead it's the long "freebore" throat, which flattens the pressure curve.

The 7mm RM's throat is very short, and erodes pretty quickly. Both result in interesting pressure variations, both when the barrel's new, and as the throat erodes.

Right. Of course when you start out with a very short, too-short throat in the case of the Big Seven, there is no reason for the powers-to-be ever lengthening it. Right?

The ammo already on the shelves would be even safer yet.

Ok...understand why the masses didn’t know...and understand the alleged reasons for factory weak sauce...why is there no real data for hand loaders. Why are we taking a large case and finding it acceptable to load to 7mm-08.7x57 levels? Sure it kills...but God damn it we have a case that holds substantialy more fuel...let’s use it! It seems the 7stw does t have these handicaps...is this fair?

What can a 7stw do with a 24 inch tube? Iirc Page’s gun had a 22 inch tube and hit over 3k with a partition 175...

Three30Eight,

Actually the big problem is there IS "real data" for handloaders. Which started with the use of electronic pressure testing, instead of copper-crusher testing. In fact, the 7mm Remington Magnum data in many manuals in the years after it was introduced used the same "seat of the pants" method of many handloaders: Work up until the rifle/case showed signs of distress, then back off "a little." Which is exactly the method Warren Page used when working up loads for his rifles.

SAAMI doesn't use this method, partly because today different bullets vary considerably in how much pressure they produce, plus testing conditions, especially temperature, or how the powder was stored. Consequently SAAMI members don't list loads that "appear" safe, but pressure-tested results, because some loads that appeared safe back in 1962 didn't prove to be in the long run.

For some reason the 7mm STW has never demonstrated the same pressure variations as the 7mm Remington Magnum. But the early "worked-up" loads that produced 3600+ with 140-grain bullets and 3400+ with 160's also produced over 70,000 PSI when tested in piezo pressure barrels. Which is why commercial 140-grain 7mm STW ammo has never been listed at more than 3400 fps.

SAAMI was set up around 90 years ago so ALL commercial ammo would function safely in ALL commercial rifles. That's still the aim of its members, and 70,000+ PSI ammo has yet to be proven to work safely all the time, because most powders vary too much in pressure at warmer temperatures--and various bullets also result in higher pressures.

If you want to push a certain bullet beyond SAAMI maximums, the of course you're free to do so.

I had to skip forward to it. Great chapter, John!!!

Or, just go buy a 7mm Weatherby Magnum and cut to the chase! Happy Trails

First of all, I believe you and think that has been proven for quite some time.....

ATST (and NOT to change anything) I well remember reading multiple Xs about the advantages of the Double Radius shoulders. As has mentioned in this thread, things THOT to be fact or true were around for a long time and just about set in concrete.

One of the first things I discovered with my chrono was this:

I never graphed a single round of Remington Factory Ammo of any cartridges -- I had -- that lived up to Remington's advertisement.


Jerry

The one thing I do know about the Weatherby double radius shoulder is that it is cool and makes the haters and nay-sayers’ screech and howl and some heads explode !!!

Somewhat related to MD’s point is the fact I’ve rarely found factory ammo (other than Norma) that wasn’t modest in terms of velocity and that couldn’t be exceeded by judicious hand-loading.

I remember Federal 270 Wby, 150-gr loads that I chrono’d at 2900 fps. I then confirmed it over another chronograph. Then there was Fed 340 Wby ammo that did the same and also confirmed, showing a good 200 fps slower than reasonably expected.

This prompted me out of curiosity to write Federal who responded so meaningfully with something to the effect of “all rifles vary somewhat.”

Perhaps understandable, as in the B7’s case, with a litiginous society.

WAM

Just for clarity, I am not a Wby hater. I've had a couple and there are a few I would like to own.

Jerry

George

I haven't bought/shot much Factory ammo but have graphed ammo for friends as well as myself.

The LAST Factory ammo I graphed was PRVI 6.5X55 in 140 gr bullets-------take a guess ?...............2250 fps. WOW!!

Before that was in 2008 I bought some Federal Blue Box 300 WM, 180 gr Speer Hot Cor ammo. Vel.3000 fps Not too bad.


I don't remember how far back but several years ago..... Federal and Winchester factory ammo was at least close to ads.


Jerry

The famous gun writer Mark Twain said it best:
There are white lies, lies, dang lies, and then there is 7mmRM published load data


Besides the big error in published data there is also the registered numbers.
SAAMI registered at 61kpsi and 3.29" OAL.
I load more like 72 kpsi 3.34" [and that has a few grains of safety margin tested in to protect long brass life in hot weather]


https://en.wikipedia.org/wiki/7mm_Remington_Magnum

The following is from the ABOVE link. (Wikipedia -- 7 mm Remington Magnum)

"According to the official C.I.P. (Commission Internationale Permanente pour l'Epreuve des Armes à Feu Portatives) rulings, the 7mm Remington Magnum case can handle up to 430.00 MPa (62,366 psi) Pmax piezo pressure. In C.I.P. regulated countries every rifle cartridge combo has to be [/b]proofed at 125% of this maximum [b]C.I.P. pressure to certify for sale to consumers. This means that as of 2016, 7mm Remington Magnum chambered arms in C.I.P. regulated countries are [/b]proof tested at 537.50 MPa (77,958 psi) PE piezo pressure.[b][6]

The SAAMI Maximum Average Pressure (MAP) for this cartridge is [/b]61,000 psi[b] (420.58 MPa) piezo pressure.[7]"

Thanks Clark --- that Xplains why MY loads have not blown 'cases', primer pockets, or primers.

-------- 77958 pse (PE) is noticeably higher than 61,000 pse (PE)


I checked my graph records and 1981 was the first year I graphed the 7 Mag. 2018 -1981 = 37 yrs. no Xplosions.


Jerry

Best answer.

I've owned several 7 RMs, and the "best" in terms of external ballistics was the 26" Ruger #1. It easily made 3015 fps from a good dose of RL22 behind the 175 NP.

The lone 7 Wby owned had a 24" tube that also made 3000 fps from the 175gr Nos. Part. from a healthy charge of RL22. Both were good shooters.

While Nosler's manual #6 suggests 2970 fps is possible for the 175gr NP, from 62.5 grs RL22, and the most accurate load, my Rem 700 gave a max of 2940 fps -- not far different from 24" barrels.

Back sometime in the eighties, I read an article from the Wolfe Publication, HANDLOADER (when at its best) that described a problem I was having with my BAR in 7 RM. It basically said that some throats were too tight and causing high pressures. So tight in fact that the brass necks were not expanding. After shooting my BAR with handloads for a month or so, I found I didn't even need to resize them as the necks were still so tight as to firmly hold a newly seated bullet! I traded the rifle at the same shop where purchased and they gave me full credit on a new M70 XTR in .300 Win Mag. No such problems with it.

So, I don't know about the reamer used by the Wiseman barrel makers, who provided the test barrel for Nosler (a 24"). It would be interesting to know if it gave a longer throat than SAAMI specs, but 2970 fps from a 24" could possibly well exceed 3000 from a 26|".

Perhaps MD could find that out for us?

Bob

www.bigbores.ca

Three,

My "un pro way" is having one o f my 7 MAGS re chambered to 28 NSLR.


Lefty C

I have owned and shot several 7RM's a lot. Set up right, it's a great round. I was made aware of the short throat issue in the 80's by a gunsmith friend of mine. He re-barreled a rifle to 7RM using a 26" Hart using a "standard" throat length. At first, I experienced problems with high pressure signs, but with lower than hoped for velocities. When I complained to him, he simply lengthened the throat. Problem solved. I have never owned a factory 7MR and never will. I expect 3050+fps with 160gr Nosler Partition and I get there with IMR7828. Under the category of full disclosure, I seldom use the big 7 anymore, I've gone to the .280AI. I'm happy with less recoil with less velocity in a lighter shorter rifle.

Bob,

All pressure barrels used by SAAMI members are supposed to have chamber (and bore-groove) dimensions that meet SAAMI standards. In other words, I sincerely doubt the Nosler pressure barrel has an out-of-spec chamber throat.

I do know that for a few years after the 7mm Remington Magnum was introduced, demand for rifles was so high that some factory-rifle chambers varied considerably in dimensions, creating problems with SOME factory ammo.

I suspect the problem with your BAR (and others) might have been due to the factory using worn reamers, to keep up with demand. Unlike custom gunsmiths, factories use relatively inexpensive reamers that start out on the upper edge of SAAMI dimensions. As the reamers wear, they naturally cut smaller chambers. Factories normally quit using reamers when they wear to minimum SAAMI dimensions, but occasionally don't, for whatever reason. The neck dimensions can get pretty tight, especially with some brands of brass with thicker necks.

Brass that's been fired and resized a number of times also tends to develop "the dreaded donut" at the base of the neck, due to the thicker brass in the shoulder moving forward. This can cause pressure problems as well. I first ran into the donut back in 1974, when handloading for my first .243 Winchester, but it occurs in quite a few cartridges, especially when brass gets sized so the shoulder doesn't firmly contact the front of the chamber--common in belted cases.

Did not intend to imply that you were! Plenty of guff on some blogs. Happy Trails

Steve

WAM

Understood. No harm, No foul.

Jerry

Looking at the Hodgdon's loading data site, It looks like the new IMR 8133 will bring some of the Joy back to the 7RM. I have several different loads of this powder under 175 Sierra BT's I will run them through my Lab Radar and see what it reads in my 26 inch factory barreled 700 DBM. I will post results when I finish testing these.

The 7mm rem mag was introduced in 1962 and if I remember right the SAAMI pressure limit was established at 61000 PSI because the round supposedly exhibited larger than normal pressure swings as mathman said, so they downloaded to give an extra safety margin. That was 56 years ago and pressure testing equipment was primitive by modern standards, plus the many slower burning powders that the round needs weren't available like they are now. IMR 7828 was supposedly developed for the round but that has been reformulated multiple times judging by the number of times I've had to tweak loads with new lots of it. I quit using it years ago. I've probably got more rounds through a 7mm rem mag than any other big game rifle I've got and I've certainly killed more game with it than any other rifle. Unless a lab retests the round with modern equipment and modern powders I'm very skeptical that these supposed pressure swings that required the round to be downloaded 50+ years ago are still a valid concern.

I treat it like any other round in that I use a chronograph and work up cautiously. My bartlein barreled M70 has a 24" barrel with a longer than normal throat. I put a .375 H&H magazine box in it to take a 3.6" round and my OAL's are somewhere around 3.5". The two loads I use are a 145 Barnes LRX at 3225 fps and a 160 gr. Nosler accubond at 3050 fps. Both use H1000 powder and I get good case life out of my Norma brass. I get good accuracy and consistent velocities with low SD's which indicates to me that I'm not getting the pressure swings that the round is supposedly known for. I don't remember the powder charges off the top of my head but they're over book max and I'm comfortable with that in my rifle.

Crowhunter,

You're mixed up on your pressure history.

The initial SAAMI pressure for the 7mm Remington Magnum was higher than today BECAUSE of the relatively primitive copper-crusher system then in use. This is partly why the initial 150- and 175-grain factory loads were much higher velocity than today, at 3260 and 3030 fps. (They were also a little higher because standard test-barrels were 26 inches long in 1962. Now the standard is 24 inches.)

Only after SAAMI started switching to piezo-electronic testing some years later was the maximum average pressure (MAP) reduced, because piezo testing was sensitive enough to detect the wider pressure variations.

This is exactly the same system used by SAAMI and major pressure labs today, and the pressure variations are still evident, and not just with IMR7828. In fact they're common knowledge among ballistic lab technicians.

A standard 7mm rem mag load shot for years was 66gr H4831 with 160gr bullets. Hodgdon listed it at 3026fps. Chronograph results confirmed it. In 1995 I opened Speer #12. It had 61gr as the max load for H4831 at 2846. Its Max load was the starting load of Hodgdons 1986 #25 book. In the mid 90's I started seeing pressure signs with new lots of H4831. It appeared that new lots required about 5% reduction in powder charges. Powder changes. Technology to test things change. We all need to pay attention to these changes. Radar chronographs changed more things. What will be the next change?

I shoot a long throat 7RM and it is very close to the 7 Weatherby. Even with the custom chamber and H870 I had a hard time getting over 3,000 fps in the 23 inch barrel 2,950 was max. for 175s. The 160s would get about 3050 fps. Did a single animal complain about the velocity shortfall or pressure excursions? Not a one did.

In a 25 inch barreled 280 AI I am getting within 50 fps velocity with R26 as in my 7RM. The 175s may out run it by 75 fps but not that much. My AI has a 1-10 twist so I stop with 160 grain bullets. The 7RM has a 1-9 and does fine with the 168-180 grain bullets. That rifle can handle up to 3.6" loaded rounds so both have their uses.

Well, "I" would have been better off looking at a handful of chicken bones on a tailgate as I suspect that "chronographs" have "ruined" more loads for me than any high pressures! ha I "wanted" that 3100+fps 160NP load (I used IMR4350 back then but didn't get there with H870 either...I called it Ol Smut-Butt powder, dirty) that I "thought" I was getting...when I finally got to shoot it over a friends chronograph ( PACT I think it was?) it was barely 2950fps. Fortunately, my 150NP load actually was getting the 3200 I was after. I blamed my 24" barrel and ever since prefer 26" on bigger cases. Just me. I'm also one who grew up hunting small game/varmints/hogs with a 30" barreled 12ga, so 26" never, ever has bothered me, ha. I've always went to or near apparent pressure "signs" then backed off a bit...never blew anything up. Sometimes its best NOT to know everything...ha

J K - Did you ever try shooting at 300---400 yds and checking trajectory/drop ?
If they are slow-------they AIN"T flat.


Jerry

I’ve heard many of the same things listed above about the 7mm Rem Mag and outside of the mysterious pressure swings many other good cartridges have suffered similar injustice. The 7 RM is a good cartridge period. So is a 7X57, 7-08, 284,280 280AI. Etc. I’ve owned a 7-08,280,280AI and shot several 7 Rem Mags. Load a good bullet at a good velocity to where it’s accurate and don’t sweat the chrony.

baltz526,

Apparently you're unaware that there have have been THREE H4831's over the years.

The first, of course, was the original military surplus 20mm cannon powder sold by Hodgdon until the mid-1970's, when their supply ran out. But a bunch of handloaders still had enough of the original stuff that many manuals kept listing the same data for another 15-20 years. (I was among those handloaders, because of being given a good supply in the late 1980's by an older handloader who wasn't hunting with rifles anymore.)

The original replacement was made in Scotland, and was evidently warmer than the mil-surp stuff. The next replacement was made in Australia--and still is. It was also reported to be hotter.

But a couple of years ago I loaded some original mil-surp H4831 (from an unopened can) and a new batch in a .270 Winchester with same 130-grain bullet, case and primer. The old stuff proved HOTTER than the latest Aussie H4831.

But of course that was only one sample. Which is of course what most handloader's "evidence" is based on.

Everything is lawyer proof now!

J K - Did you ever try shooting at 300---400 yds and checking trajectory/drop ?
If they are slow-------they AIN"T flat.


Jerry[/quote]

I finally got permission to set up on an old farm road. Measured out to 600yds. I had a home made steel pendulum target made up (8" square) and had a ball for a couple years! Even though that 160NP load was "only" 2950, it was running plenty flat! ha BUT...it 'wasn't" the 3100 I had read about in Bob Hagel's writings!!! I even wrote ol Bob a letter and asked him about rechambering to the 7mm/300 Weatherby. He wrote back and said my 24" barrel would negate any real gain over the Remington. So I was bummed. Funny thing is, I "never" killed anything with that 7mm Mag that was further than about 50yds...well, some crows out about 150....being in the "Big thicket" didn't help my experiments, lol.

Seems the older, mil surplus stuff may be a bit slower than some of the later versions. I guess that can vary from lot to lot.

I have a few pounds left, still smells good, no brown dust, shoots very well.

DF

I don't know why your 7 Rem Mag is underloaded. I don't have one but if I did I certainly would not underload mine 😁


Trystan

agreed x2 as I posted earlier its all about $

I have heard about these "pressure spikes" before, do they appear in all belted mags or just the 7RM? What causes them?

I carried a 7RM as my fishing gun in Alaska (only rifle I owned at the time) and my Pee Pee din't feel compromised in any way. Looking back in retrospection the 7RM is just a little bit better than the 30-06 and 270 with 160-168 grain bullets. Comparing it to the others is not damning by faint praise but acknowledging it is a right useful cartridge.

Let the banter continue.

RE: Pressure spikes, if you ever have to feed a brownie some lead the pressure spike would only be an asset.

Read Mule Deer’s posts earlier in this thread

+1

I think the bottom line is short throat/short neck.

My 7RM has a 3.6" mag box, throated for VLD's with longer COAL's. Don't think that combo will have much pressure variation, seems to have low E.S. and S.D.'s with good accuracy. The Brux barrel probably contributes.

DF

"Even though that 160NP load was "only" 2950, it was running plenty flat! ha BUT...it 'wasn't" the 3100 I had read about in Bob Hagel's writings!!!"

I seem to recall that Bob Hagel had his Remington M700 throated out longer so that he could load hotter. I don't remember if it was in his book, a magazine article or a question asked by a letter to the editor and his response. I believe it may have been the latter and was in either RIFLE or HANDLOADER. I'm surprised I even remember that as it was quite a few years back.
Paul B.

I did, I guess I just missed the specific reason the first time through. Just to be clear, this means that the bullet is forced into full contact with the lands/grooves too quickly and that is why the pressure spikes? As opposed to a Weatherby which has a longer ramp down to bore diameter?

Thanks.

Actually it was mathman, on this thread, who paraphrased what MD has stated in the past, to wit:

"Pressure isn't constant shot to shot. Modern testing equipment is able to show that the probability distribution of the pressure for the 7mm Rem Mag is spread out somewhat more than other cartridges. So the loading was changed to lower the mean pressure of the distribution enough so the area in the no go portion of the high pressure tail of the distribution became acceptably small."

As I understand it, we don't know why this particular cartridge demonstrates wider variations in shot-to-shot pressure. (the 243Win is another). On this thread, MD referenced mathman's post and then pointed out some additional reasons why factory pressures were reduced.

I thought I was missing it, but if know one knows, then that is why I didn't pick up on it. ;-)

I am surprised this doesn't happen with the 264 WM same case and 0.5 mm difference but apparently it is not the case causing the spikes.

That's interesting. It sure raises a real question or two.

OR, ?maybe? with the 264s lack of popularity, the phenomenon hasn't been publicized ? ?


Jerry

7mm bullets are longer...??

That may make some difference, .264 vs. 7RM, not sure.

I think the .264 came out before the current 6.5 phenomenon. It is a good round, however I found it to be more finicky than the 7RM.

DF

I am thinking it is partially due to the powder. MD doesn't think so, but the 7RM and 243 which had pressure variations were loaded with 7828. The 264 with Winchesters 860-870 series ball powder (not sure exactly which one). Even though these powders and loads have changed we don't see the pressure excursion in other cartridges with 7828 I doubt that it would be undetected.

The 264 had a short throat but most of the early bullets that were 264 Mag specific were two diameter bullets to reduce pressure. I don't recall this ever being a problem with the Weatherby cartridges so this could indicate that the throat/leade/freebore is a factor too. Gun Geek speculation.

Tejano,

As I noted earlier, the phenomenon has been noted in the 7mm Remington Magnum with far more powders than 7828. I know this from visiting several major ballistic labs.

The same thing applies to the .243. The guy in charge of one of the Big Three ammunition companies told me it occurred in the .243 only with bullets in the 100-grain class, not with lighter bullets.

Fellas - all y'all

What I'm about (fixin) to say is NEITHER positive NOR negative, just my stats and observations.


I have copious chrono notes dating back to 1981. It would take me a LONG time to go thru and count the # of times and # of rounds I have chronod with various 7 RMs.

I PROMISE..... I do NOT have ONE velocity (speed) reading that rose ABnormally from the rest. Yes, some rifles (barrels) were a little faster/slower than others but NO readings indicated EXCESS pressure.

*** NOTE *** The majority of bullets I've graphed have been 139 BTST, 150, and 160 N Pts. I have NOT messed with 175s at all.
PLUS - I have NOT used IMR 7828 at all in the 7 mag. I use these: IMR 4350, IMR 4831, and SURPLUS 4831.

I have NOT come to any conclusion on this phenom. I can only speculate with those bullet weights and powders I have NOT seen any evidence of pressure excursions.

******** "Pressure = Velocity" or Velocity follows Pressure.


That's my Story..........


Jerry

An ADDENDUM:

I have a notable example of excess pressure from my graphing the 270 Win.

With the Scottish H 4831, LOT # 9181, 62 grs yielded 3200 + fps. It didn't blow the primers but there was noticeable resistance in bolt lift.


I never experienced any of that with any 7 Mag.


Jerry

Roughly speaking in mathematical terms, velocity follows from integrating a pressure curve, and integration is a smoothing operator.

Jerry: and FWIW, I will reiterate what MD has told us numerous times: traditional pressure signs (primers, brass head expansion, bolt lift, etc) do NOT appear until pressure is well above what is considered "safe". And don't ignor the fact that stress on the action/barrel is cumulative.

I had 35 gr bullets in a 223 with Blue Dot powder.
At 18 gr some of the shots had no extractor groove growth an 4100 fps
At 18 gr some of the shots had 0.0100" extractor groove growth and 4200 fps

For those used to plotting data and seeing smooth changes in dependent variables, this is scary.


This is a 7mmRM loaded at 107 kpsi quickload with Re17.
It caused slight deformation to the VZ24 bolt and the receiver abutments. Once pounded out, the bolt would not go back in the gun.
A little valve grinding compound returned the clearance. I then shot an antelope with the rifle.

The rifle was a 7x57mm South American military rifle, but I rebarreled and opened up the extractor, bolt face, feed lips, and magazine length for 7mmRM.

This post is NOT directed AT nor limited to southtexas: I was going to post this before I opened the thread just now.

The following pic has been posted before but is appropriate here.

-----DISCLAIMER -----
These loads were slowly worked up to in MY rifles. I DON'T recommend that anyone copies or uses them w/o proper caution.


This page of records comes from Aug. 1997 ---> 21 yrs. ago.




This graph session involved my 700 Syn 7 RM

***NOTE the first average line WAS graphed in my 700 BDL (more later)

The Syn topped out with 67 grs. * There are 4 (FOUR) lots of IMR 4350 graphed here.
I've been shooting 67 grs w/139 BTSPs for 21 (Twenty One Years)

Now BEFORE anyone loses their cool: This page is in Horn Vol II



Note the 4th line from the bottom shows 68.2 grs 4350 -- (at that time there was ONLY IMR 4350) AT 3300 FPS.
Remember I've been shooting this load for 21 years.

**ALSO the 4831 in Horn. Vol II is SURPLUS 4831. I verified that years ago.**



Now per the BDL 700, I don't remember what year I got it but it was well before 1997.
The BDL 7 RM absolutely DOTES on 68 grs of IMR 4350 AT 3300 fps. I've killed quite a few WT and coyotes with the BDL & 68 grs.

BTW--- it is STILL in tact.



ONE MORE TIME, I'm still NOT recommending these loads

NOR have I reached a conclusion about pressure variations (excursions). These loads have worked for me MORE than 21 years and I still have the USABLE rifles as evidence.

Jerry

ps: I hope I covered all I wanted to cover.

Hodgdon says 7mmRM 140 gr NBT H4350 that 59 gr is the max load.

I have (9) 7mmRM rifles and they all like 70 gr better. [11 gr extra is 19% extra]

12 ruminants have died.

I probably could have used 56 gr [Hodgdon starting] or 72 gr [beginning of extractor groove growth] with the same results.

Here's a link showing 7mm rem mag data from the A square manual with changing pressures and velocity due to primer substitutions.


"Any Shot You Want (A-Square's manual) has similar data, for the 7 Rem Mag using H4831 and a 160 gn bullet:

fps psi

Win WLRM 3045 67600
Win WLR 3024 64400
Fed 215 3036 61400
CCI 250 3039 61500
Rem 9.5M 3041 59300
CCI 200 3011 54800"

Going to a magnum primer caused pressure to rise by almost 5% but velocity to change by less than 1%, small enought that you wouldn't catch it on a chronograph.

That said, I should a 7mag and think its the greatest thing since sliced bread. I've decided that so long as the pressure swings are small enough that you need pezio to see them I'm not really going to worry about them so long as I load to a sane velocity.

Kellywk

I am of the same “opinion”. Minor variations IF they don’t show up over an O 33.

Loading 7 R.Ms since 1981.......ZERO shrapnel.

Jerry

First, that’s LAUGHABLE !!!

When I bought my Nosler 7, I posted here,

“For many years I browsed thru new manuals....yawn !”

Nosler 7 is pretty good IMO.


Jerry

Nosler #7 says 65 gr IMR 4350 -MAX — 140 bullets
That may be for 140 N P which usually generate more pressure.


Jerry

Well...dumb question on my part but i want to work up to some decent velocities with 160 and 175 gr bullets...what are my best best for powder and where should I start...

So velocity is a function of the area under the curve? Therefore a pressure spike may or may not be apparent on a chronograph.

Right, it may or may not be apparent. Please don't read into this that chronographs aren't valuable tools for keeping us out of trouble however.

M M






Also, Hornady Vol II 139 SP, 68 gt IMR 4350 - Max


What's a reloader to do ? ? ? Loading data is ALL OVER the place.


Jerry

Mule Deer

Same ??

What’s a reloaded to do ?
Which book/loads do you believe - where do you start & stop ?

Jerry

3308 - First I have not loaded or shot one 175 gr in any. 7 RM. So no comment.

I have Xperimented with 160 N Part.

FROM -> IMR or H 4350 - - IMR 4831 - - H 4831 - - Rl 22 - - Rl 26, - - H 1000 - - IMR 7977
Those powders will work with 160 NPs. I’m sure there are a few other powders appropriate.

*For ME, I chose I 4350 for economy to get ‘close’ to top velocities.

The slower burning powders burn more grains per shot.

Because of the nature of THIS thread.... I can in good conscience suggest that you START at Starting charges and
STOP when you reach a SANE velocity for the bullet. -*-* I hope you have a chrono or have access to one.
I was fortunate in that I had a chrono WHEN I started loading the 7 Mag.

In MY 700 BDL 7 RM I was able to get 3100 FPS with 160 NP without damaging components or Rifle parts.
That’s the best I can do in recommendations.

Good Luck

Jerry

M D - Mathman - Denton - et.al.

I'm asking a sincere ? here. Any suggestions.


Jerry

Jerry,

The best sources of data tend to be the newest manuals, for several reasons:

The data in some older manuals was developed the same way some handloaders work up loads, by adding powder until the rifle and brass showed signs of distress, then backing the charge off "a little." Or they used copper-crusher pressure barrels, which require a bunch of careful measurements to work correctly. At least one company started using copper-crusher barrels, then couldn't get consistent results, probably because they didn't control other factors (such as temperature) or measure very carefully, so went back to working up loads the old-fashioned way.

Many companies also tended to use the same "pressure barrel" for many years--which often was a factory rifle, not a closely dimensioned pressure barrel. As a result, the throat often eroded considerably. This affects pressures in two ways: At first pressures tend to rise as the throat turns rough, but after erosion widens and lengthens the throat, pressures drop.

I've visited a bunch of pressure labs in the past 20+ years, and haven't run into one yet that didn't work in a temperature-controlled indoor range, with electronic testing equipment and SAAMI-spec barrels. Which is why recent loading data's more consistent, as I've explained in a couple of my books.

Today, perhaps the biggest factor in handload-data variation is bullets, because their construction varies so much, followed by powder-lot variations.

jwall,
Didn't see John's above post until I after I posted mine but I'll leave mine here anyways.

If you can get your hands on HANDLOADER #209 there is an article by JB entitled "How to Read Reloading Manuals". For me it answered the questions I had back then (2001) same as what your asking now plus more. I'd post a quote out of it that sticks in my mind to this day but won't for three reasons. First and foremost I don't know if I'd be stepping on John's toes by doing so. Secondly I wouldn't want the quote to be taken out of context And thirdly I don't know if the technology has changed since then to the point that it would influence the data in the newer reloading manuals or if John's always on going research since then would add to or remove from the contents of that article. For me the article was an eye opener.

M.D. : What you just posted makes a lot of sense somehow that needs to be known more by everyone who shoots a gun,somehow that needs to be addressed and for everyone including myself not to use older ammo reloading books and somehow figure out a date or reloading manuals that are still valid and safe to use. this is a huge safety concern that somehow needs to be advertised much better ? I have also been in a testing rifle /pistol ammo factory too and all reloading equipment,bullets,powder,guns are in a dry and temperature controlled tunnel with no sun rays or wind either, so what we as simple handloader`s do is in a more natural outdoors environment and our indoor storage areas, older powder,temperature control is for sure not as good either. good luck with it,Pete53

Yes it did, the fact is both 150 and 175 gr Remington 7mm Corelokts are 2 DIAMETER bullets also. The bullet in front of the canelure rides on top the lands and the front edge of the canelure on back to the base to the bottom of the grooves. That is monumental amount of difference in how much full diameter bullet you are pushing thru the bore which changes the pressures significantly. I know for a fact that the 150 gr bullets kill just fine but no better than 140 NPT's ,solid bases ,139 gr hornady's . Sierra's shot fine but did not hold together for me. Some friends of mine have reported satisfactory success with the 175 gr but I haven't used on game yet. I have a significant qty of both 150 & 175's yet to play with,so it will happen. Mag Bob

Thank you Sir: I really did read all of your answerS, just edited to specific points,
I DO trust you and BELIEVE you.

I myself with ONLY a good chronograph have run into those LOT/LOT variations--- AND in Brass also.

Thank you for taking the time to respond. It seems to me that TODAY handloaders NEED a chrono more than before.


Jerry

ps: I still like Hagel tho:

Following the advice of a number of the old time gunwriters can lead you to trouble. That whole "work up until you see obvious pressure signs" scares me.

Thanks Jerry...much appreciated. I do have a chrony...and will proceed with caution.

Back in the day before modern electronic sophistication, seat of the pants cowboys ruled.

They weren’t much different than the rest of us who were doing about the same thing.

High tech gadgets and lawyers have changed the game and the results.

Not necessarily a bad thing, IMO.

DF

Think slow for the 175s. I have had good results with H4831 (old stuff), MRP, R22, H870, R25, AA8700 and now trying R26. There are book loads for all of these. I think R25 and R26 may be the stand outs. H870 shot well but some of the old lots I had were almost like shooting black powder it was so dirty. Some of the surplus powder places have the 800 series powders if you want to experiment cheaply, but I have no idea on temperature sensitivity and how well or clean they burn. At full power not too bad but nowwhere near the more modern powders.

Thanks EZEARL - I'll try to find/get one.

Jerry

Mike in View of MD's response - the best we can do EVEN today DUE to wide variations from 'manuals' - is compare multiple sources of data per the bullet you want to use ->->-> then graph till you get in the ball park, >> Being careful along the way.

The bottom line is There Is No Absolute in Handloading.


Jerry

Ackley 1962 page 148 quoting load book author Vernon Speer 1958, "pressure gun... exceedingly unreliable...we use case head expansion in determining pressure..The cartridge is the weakest link in the modern bolt action rifle. If the pressures at which these cartridge cases are fired do not exceed the elastic limit of the unsupported rim of the cartridge case, then we consider that the pressures are entirely usable, regardless of what they might be....excessive pressure... reduce charge by 6%...list as a maximum load.... softer... Norma cases..."

a) 60 years later the temperature stability of H4350 and IMR 4451 allows me to reduce his 6% margin for load book writing to 2% for my personal hunting loads.
b) I measure the extractor groove all the way around before and after firing. Ironically, this is a much more precise predictor of loose primer pockets than measuring primer insertion force.
c) 60 years later Norma is still selling soft brass. 7x57 rimmed necked to 257 Roberts Ackley rimmed should be good to 80 kpsi, but it is only good to 60 kpsi with Norma brass.

Clark

Vedddy in ter resting. !!


Jerry

Semi Related -- Didn't know a better place to put this;

I snagged 4 lbs. of H 4350..... HazMat FREE-->--> Natchez Offer Good Thru 8/1/18 -->-->***** Promo FH180725*****
They also have 8 lb jugs too.

Thank Me Later


Jerry

ClarkM,

The reason Speer found the pressure gun "unreliable" is that apparently nobody knew how to use it consistently--meaning making all the necessary measurements, under controlled conditions.

A major piezo-electronic lab tested the case-head expansion theory a few years ago, with three different cartridges. They loaded them using "traditional" methods, including CHE, and one cartridge was spot-on, another considerably under pressure, and the third was over-pressure. The reason, of course, is brass varies widely in hardness--though I haven't found any soft Norma rimless or belted Norma brass in probably a decade.

The reason 7x57R cases are relatively soft is they're meant for break-action rifles, including drillings, where brass needs to be a little softer to reliably seal the chamber, since they don't always operate very well at typical bolt-action pressures.

Why is the 300 winchester magnum underloaded today? Most factory 180gr ammo runs under 3000fps, but IIRC in the past more than a few factory loads were around 100fps faster.

BWalker,

When the .300 Winchester Magnum was introduced in 1963, the listed muzzle velocity for 180-grain bullets was 3070 fps. But back then the standard length for test barrels was 26 inches, and Speer's No. 6 manual (published in 1964) ran a chronograph test of a bunch of factory ammo in typical rifles. In a Model 70 Winchester with a 24-inch barrel the factory 180-grain ammo got 3000 fps.

Until recently the standard SAAMI muzzle velocity for 180-grain bullets in the .300 Winchester Magnum was 2960 fps, which is indeed pretty wimpy. But today SAAMI lists three velocity levels for 180-grain factory ammo, up to 3080 fps from now-standard 24-inch test barrels.

Thanks for the insight, JB.

I've had great results with RL-25 and 175's in my 8 twist Brux 7RM. RL-26 may be even better with the heavies. I have a jug of RL-26, just haven't had time to check it out.

DF

FOLLOW UP ! 4 days to delivery.




They arrived today. IMO that's pretty good - 4 days including the weekend.
This is my first time to get any H 4350. All 4 lbs. are the same lot #, so for better or worse it's all the same.

Jerry