As I study the 7mm Rem Mag and 7mm Weatherby Mag cases, it strikes me that they are virtually identical except for the radiused shoulder angles on the Weatherby.

The big difference between the two cartridges is, as best I can tell, is the SAAMI pressure limits � the 7mm Rem Mag runs 52,000 CUP and 61,000 PSI while the Weatherby runs 65,000 PSI. (Hodgdon data shows Weatherby loads in excess of 55,000 CUP.) By contrast, SAAMI ratings are 65,000PSI for the .270 Win and 64,000PSI for the .300 Win Mag.

Given that, and given a modern firearm that is commonly chambered for the .270 Win or .300 Win Mag, I question why the 7mm Rem Mag can�t be loaded up to similar pressures?

Thoughts?

"Back in the day"...it was discovered the 7mmRM in particular had a quirk of wild pressure spikes. .243Win same same IIRC. Just an unexplainable quirk of the round. The 61Kpsi is just a safety measure. In theory 65K should be and would be safe, but that safe pressures are tallied at a max AVG safe pressure, and to maintain a 65K AVG, the top end spikes tend to be too high. Mule Deer (JB) explains this very well. But basically thats it.

I first read this theory on this very website some years back, and in the interim have spoken with several ballisticians who to a man disavow it. Rather, I have been told, the 7mm Rem Mag displays a wider pressure band, or in other words wider "swings" in pressure, low and high, not "spikes" upward...

So why is the sammi max for the 300 win mag at 64,000 instead of 65,000?

That may be right...cant say for sure. I'll take your word. But the bottom line is that the top end spikes were too high to be considered safe at an AVG of 65Kpsi, regardless of the low end.

BW,

The numbers put out by SAAMI are a "maximum average safe pressure." They have to look at the top end pressures some loads get...if they go over a certain number, the top AVG must be reduced so that the MAX pressures don't exceed XXpsi. I'm sure thats a simplistic explination...but basically thats its.

If you really want this in detail, Id suggest asking the GW's.

I�ve never bought into the idea that the 7mm Rem Mag (or the .243 Win) were unique in any way when it comes to pressures. It makes much more sense to me that other factors were influencing the results seen and that the results were subsequently misinterpreted.

At any rate, I�m not seeing any reason why the Weatherby can be safely loaded to 65,000 PSI and the 7mm Rem Mag cannot. (Or why the .264 Win Mag and .300 win Mag are safe at 64,000 PSI and the 7mm Rem Mag is not.) The 7mm Rem Mag and Weatherby cases are identical for all practical purposes, with no physical reasons I can see that account for the difference in powder charge levels. (I am open to correction in my thinking, however, if solid evidence can be presented that shows my thoughts are wrong.)

At any rate, the reason I�m asking is that my 7mm Rem Mag 160g North Fork loads at 3048fps are redundant with my .300 Win Mag 180g loads at 3032 and 3048fps (TSX/MRX and North Fork, respectively). As a result I�m working up loads for 140g TSX/MRX and would like to hit 3250fps.

Based on the work I�ve done so far with H4350, H4831SC and H1000, I think I can get there with a couple powders, maybe all three. To do so looks like it will require exceeding 7mm Rem Mag max loads but stopping short of or at 7mm Weatherby starting loads.

The twist rate is differant. Even Weatherby twists the 7mm Rem 9.5" And the 7mm WEA 10". Reminton twists the 7mm Rem 9.25"


The faster the twist the higher the pressure. And I would think the more likly to creat spikes???

Have pondered the same question myself. I've measured case capacites of both cases and they are almost identical. I attribute a slightly higher velocity and associated powder charge to the Weatherby freebore. Most 7mm Wea data states that the data was developed with standard weatherby chambers which have freebore. The freebore allows a couple extree grains of powder vs the 7mm RM. Even acounting for the freebore, there seems to be an abnormally large gap between Wea and RM data...........

Might also add that most of the 7mm RM data stops at less than 60K psi; presumably to account for the wide pressure band.

To me though, there is still a big difference in safe velocities between the 280 and 7mm RM. Both have ~ 60K psi SAAMI limits and the RM is 20+% larger. That's about 5.25-5.5% more velocity for any given bullet weight or ~ 150-200 ft/sec.

Or stated another way, the 280 gets 94.5% of the velocity of the 7mm RM - 160's ~ 2800, 140's ~ 3000.

Boys, I'm merely repeating what I have heard as the reason. I think JB has explained it here too. What you choose to believe and the pressures you choose to load to are a matter of personal preference. The published velocites, which I assume are acheived at SAAMI pressures, are plenty for me. With that said, the .280 is a different animal as to why its not up to the 65Kpsi mark...and I load it to 65Kpsi standards. So, I get what you're saying. In fact, thinking on it, it could be the difference is the 7mmRM is loaded in so many configurations...Autos, pumps, Singles, Bolts...so...who knows.

BW,
I am sure that you are right regarding the freebore in the "Roy". Very similar to backing up a bullet in anything. The closer you get to the lands it seems the higher the pressure given everything else equal. As I am sure many know some barrels and chamber combinations are more and some are less sensitive to added powder (out of the book loads). I had a 7MM RM on a Mark X with a Douglas SS barrel that would go over with a 145 Speer and anything over 65.5g of RE22. Another .2gr of powder and it was burnishing the bases. The Speer manual says 68g is max. No way with this rifle. Later I found that the lot of RE22 I was using was a very hot lot which is what probably caused the low capacity compared to published capacities. Given all of that and after replacing a couple of barrels on that 7MM I decided that it wouldn't hurt to slow them down a little. Running a 7 or a 300 at max or out of book powder charges looks good on the chrony but it sure is hard on rifling. If a man want to run a RM at "Roy" velocities it might be a good idea to just buy a "Roy."

1

The real differenc between the 7 rem and Weatherby is, I think, the freebore. I've built 3-4 7 Rem Mags with "long throats, that is, long enough that the 160 Nosler Partition was seated with its base even with the base of the neck. It takes a H&H-length magazine box to do this.By the way, ALL my costom barrels have been Douglas 9.5 twist, or Kreiger 9 twist.Loads weresimilar to the 7 Weatherby.

Set up this way, it was very easy to get 3130-3150 with a 160. Friends did the same with their rifles, so we shot thousands of rounds set up this way without a problem.I hunted with a rifle set up this way for about 10 years all across the west, no problem.

Federal emailed me in response to a similar question to say they load the 7 RemMag to 58,000; the WSM to 63,500 psi.

I think this pressure spike issue has nothing to do with the cartridge itself, but to the wide variation of chamber, throat, and barrel styles in the various rifles chambered to it after it came out.I say this because I have recorded chronograph data showing 2 different 7 Rem Mags giving velocities varying over 200 fps from the same ammo, same day, same everything except the barrel.I have found, for example that my Douglas barrels have given higher velocities with the same charges than the Kreigers do; said another way,it takes heavier charges in the Kreiger to hit the same velocity levels.

I have even built a couple of 7 RemMag barrels with "oversize" groove diameter,ie. 285 instead of 284 groove diameter.(I have done the same things with a number of 300 WM's and 270's)This actually worked very well, the barrel not being prone to touchy pressure increases as near as I could tell, and accuracy still excellent. The charges will. however, be a good deal heavier than what the manuals show.

I have generally used the cartridge with 140's at 3250-3300, and 160's at 3050-3100 without any incident.Don't know if this helps, but there it is.

I don't think that's it. If a ballistician from lab XYZ said he measured a certain variation in pressure from shot to shot in a test string I'm inclined to believe he used the same test set-up for the entire string.

Also I don't believe the words "pressure spike" convey the right meaning. My take is that sample probability density functions of pressure test strings for the 7mm RM have more weight in their tails than do sample pdfs for other cartridges.

mathman

How about a loose conversational thought experiment, with differences exaggerated to illustrate the point? Note that I'm not trying to put a physical cause behind the observables. I'm taking a shot at why loading recommendations are different given the observables.

Suppose that cartrige A, when loaded to an average peak pressure of 63,000 psi, never has any individual shots in a test string measure outside of a narrow window. Let's say [60,000 , 65,000] psi.

Suppose that much testing has produced data showing that cartridge B, when loaded to the same average peak pressure of 63,000 psi, typically needs an interval like [56,000 , 70,000] to catch all the measurements in a test string.

Certainly cartridge A could be loaded with it's average peak pressure set nearer the individual maximum allowable pressure without having particular shots going over the individual MAP.


My take is that modern faster acting pressure measurement methods that report pressure-time curves have shown test ballisticians that the 7mm RM is more like B than A.



What other factors cropped up for these cartridges that could not have just as easily affected the tests of others?

mathman

I like your example mathman.
I have heard for years that the 7mm Rem. has had issues with pressure variance.
If I owned and loaded for a 7mm Rem(I don't) I would simply keep my loads on the mild side.

Mathman: It could be as you say; I really do not know. What is curious is the same "problems" have never been noted for the 7 Weatherby, a cartridge with about the same capacity, using the same bullets at about the same velocity. Why one should be subject to erratic pressure variations, and the other not, makes me suspect of the research.Could be Gremlins.....

Along the same vein, I remember an article by, I think, John Haviland on the 30/06 in Handloader, where he discusses Charlie Sisk running into strange pressure variations of up to 12,000 psi in a customers' rifle that did not manifest themselves in velocity variations, but showed up in erratic grouping. Sisk traced it back to primers, curing the problem by switching to fed 210's. I do not remember the cartridge which caused the problem, but don't think it was a 7 rem mag. Some here may remember the article. Point is,many other cartridges may be prone to the same problem, if it exists.

Anyway, it is very clear to me that,at least, variations in barrels and throating can make a significant difference in velocities and pressures with the same components.It is very hard to keep things exactly the same all the time.

Bob,

I think significantly lengthening the throat on the Rem. basically turns it into a Wby. and so the initial pressure rise is smoothed off a bit. It may be that this capacity/powder/bullet combination gets along with available propellants better with a little freebore, regardless of whose name is stamped on the case head. Sound reasonable? I'm sure not claiming I can explain it.

mathman

Bob,
Your right on the money about diferent combinations producing different velocities. Here is some data from this morning that is pretty interesting.
8:30AM 65 degrees No wind (all flags still), clear sky.
7MM RM Sako 75 w/25" Spencer barrel

66gr RE22 140g Nosler CT 5 Rounds on a clean barrel
2927, 2895, 2924, 2905, 2955

Gonna keep working up with this load and will have more results tomorrow. Accuracy was OK but not great.

64.5gr IMR4831 150 Nosler BT 4 Rounds on a clean barrel
3028, 3051, 2973, 2979
Group size .249" Fouler was 1/4" under the last three shots in the group that were all in a cluster touching.
This barrel might be one of those that isn't going to shoot big velocities but it looks like if a guy can hold it still it will shoot where it is aimed.

mathman -

I understand what you are saying but without hard proof I have a very hard time accepting that the Weatherby is well behaved while the Rem Mag misbehaves badly.

The difference in twist rates (Modern Rugers use a 1:9.5 and I assume my 1982 model also does) may play a role but the Weatherby's are 1:10 so I'm not convinced. Freebore could also play a part but my Rugers tend to have lots of freebore (I often joke the bullets couldn't touch the lands with a stick, and I load to max length allowed by the magazine as a result).

There are no factors at play that could not have cropped up in testing other cartridges, at least none I'm aware of. Still, I don't believe there is anything about the Remington Mag that would cause different behavior than other, similar cartridges. But as I said before, I'm willing to listen.

I don't think it's that extreme. I believe a truly touchy one is the 7mm RUM, but I can't point out a reference on that right now.

I'll check in later if I've got any gas left in my tank after the football party I'm going to.

RaceTire: You may be able to sneak up on 68 RL22 with the 140. I've used that load a good deal in my rifles with no problem.When I hit 3200 with the 140, I stop, so long as everything seems OK. Some rifles give more; I don't worry about it if everything seems OK. I'm not surprised that Spencer barrel gives "bug-eyes" groups!

I'm about to start all over with a new Kreiger 24" 9 twist; we'll see what happens!

First bullet I'll try is the 140 Accubond (Jeff......are you out there....listening....see this?........

Mathman:This whole thing is sort of puzzling for sure, but here's the deal. Near as I can tell, if you work up a load in your own rifle, make it reasonable, and use it continuously; and accuracy and velocity are up to what the rifle should give, I don't think you'll have a problem. Over the years that's what I've done and I have frankly never blown a primer or had other indications of problems with the 7 Rem Mag, and wore out more than one barrel in the process.

Regardless of what cartridge gives it, a 160 7mm bullet at 3100 fps is a deadly open country load for a lot of big game here and abroad. And while maybe not quite in the class of a 180-30 at the same vel, it cuts a pretty big swath, and not many feet will seperate the animal hit with either IMO.

I've run 70grs of R-22 with 140s @3300plus. No probs. Actually ran 70grs of R-22 with 150s @3250fps. Seemed a wee warm to me. 66grs of R-22 is juuuuuust right with my 160AB's @3080.

Any thoughts on Warren Page or Bob Hagel's experiences with the 7mm Magnums ?

Having loaded for quite a few 7mm rem mag rifles,including four of my own,I found the cartridge to be just as consistent and predictable as most other cartridges.

Well, here's the deal. Tomorrow I head to the range with 140g TSXs over H1000, H4831SC, H4350 and Retumbo. I'll be there all day and will have plenty of time to chrono the loads while letting the barrel cool between shots. If I find what I'm looking for I have some MRXs I'll use next.

I also have work-up loads for my .308 Win and .30-06 (both with 165g MRX, having done the preliminary work with TSXs). Tomorrow is a club Hunter sight-in Day and I'll be functioning as a Range Officer. There are usually plenty of periods where there are no other shooters and I have the range to myself, so shooting the loads should be no problem. Regardless, I plan to get there early and get some of the work done before anyone shows up.

Should be an interesting day, Hunter Sight-in Days always are.

Coyote: Post up the chronograph results. I gots to know.....

280: Just checked my notes on my custom 7 mag ( a Len Brownell rifle built in the 70's; think the barrel is a 24" Douglas). 68 -RL22-140 Partition gave 3260.A friend called from NY yesterday. His Dakota with 24" Kreiger 9 twist gave in the high 2900's with 140 TSX and 67 RL22. I told him add more powder and watch the chronograph and other pressure signs; I'm guessing, like you said, he'll max out about 70 grains. Barrels really do vary a great deal, and 7 mags are not unique in this way.

Completely agree! My father had 2 custom .280s, though I can't recall the bbl makers...the top end loads were no where near what I can do in my factory remmy's...the tight chambers showed pressure signes early on. Or maybe the bbl was cut tighter...who knows?

280: I very strongly suspect it is the barrels/throats,smoothness, dimensions,etc., each varying in the amount of resistance created to the bullets' passage.Have a Kreiger cut with a .285 groove diameter , if you really want to freak-out!

Here�s the velocity results of today�s testing. Each powder test consisted of one load at each powder charge with 0.5g increments. None of the loads exceed published Weatherby data.

Please keep in mind my Ruger has a long throat � the numbers posted may not be safely achievable in every rifle.

7mm Rem Mag Federal brass
CCI 250
140g TSX

3228fps = 68.5g H4350, unacceptable accuracy
3246fps = 73.0g H4831SC, good potential
3097fps = 75.0g Retumbo, excellent accuracy (but not the velocity I was looking for)
3303fps = 77.0g H1000, unacceptable accuracy

Note that accuracy refers to any 3-4 consecutive shots since each load was different by 0.5g. A further note: Previous tests indicated I could only get about 74.0g of any powder in the case to the bottom of the neck. The top two Retumbo loads pushed the bullet out a bit overnight. The top H1000 loads did not.

Coyote: Looks like the H4831 load to me; vel is where it should be and accuracy OK(?).

So 'Yote Hunter - I've long been using the 160 - 175 grain bullets from my 7mm Rem mags, with good results on critters from coyotes to elk.

Do you think that 140 Barnes TSX pushed to 3200+ fps would be a decent elk & black bear load? Or is the bullet too light for that? I went with the 175 Nosler Partition at about 2900 fps for my elk load some years ago.

Curious... Thanks, Guy

Two of my hunting partners use the 140gr tsx for elk and moose.They work at least as well as the 175gr partition,if not better.

Guy-Im with Stubble on this for sure.

The last elk I took with a 140 out of my 7 Mashburn Super was @ 520 yds. The bull was broadside when I dropped the hammer.

He hit the turf so hard he bounced. The 140 TSX took out both fronts and exited.

I'd say it is plenty enough for elk.

For years I used the 160 and 175 Nozlers, I can see no difference between the lighter TSX's and the heavier Nozlers.

Good luck to ya!

Dober

That settles that!.........

Bob,

Your experience with long throated 7mm Rem's mirrors mine.....had 2, gave one away so now have one. Both Sakos.

I use RL22 with 160 Noslers loaded to base of the neck and get 3150 FPS.

The powder charge is over any manual I've seen but is completely compatible with my gun and I've used it for a long time w/o issue.

I also have a 7mm Wby. on a Win action and it dupes the load and velocity.

I also believe that "back in the day" with the 7mm Rem was introduced, there was a lot of variation in chambers & throats which led to a lot of pressure swings, hence reduced pressure specs. There is nothing intristic to the cartridge itself to cause pressure swings.

Most factory stuff is really anemic; I've chronoed Fed. Premium 160 Noslers and they didn't break 2800 at the time I checked them......maybe they've adjusted more recently...........don't know since I've not checked any factory stuff lately.

MM

MM: I recently fired a bunch of 150 Fusion through a Hawkeye 7 Rem Mag, out to 500 yards. Zeroed 3" high at 100 (the way we old guys do it), the stuff was showing about 2 feet of drop at 500. I did not clock the stuff but would guess it to be at or a bit over 3000. The Federal 160 Partition has always clocked in the 2800's, while my handloads through a standard throat rifle were always 3000-3100.

"Long-throating" the 7 rem mag and 300 Win Mag was the work of guys like Bob Hagel, and John Wooters, who saw a benefit with the powders available back in the 80's.I stopped doing it because my original M70 custom 7 mag finally wore its' barrel in the early 90's.By then we had RL22, and other powders that allowed me to hit 3100 or so with a 160, so I called it good, and let 'er go at that.

With stuff like RL25, 7828, RL22,etc, getting 3250 w/140's, or 3100 with 160's is not a problem IME, with standard throats.The cartridge is as effective a moderate recoiling, open country load as it is possible to get, with a flatter trajectory than either the 30/06 or the 270. Even the newer, hotter 7mm's don't shade it by much. I hear that a lot of people are trading them in for newer, trendier creations.If they think they are buying more game-getting ability, they are kidding themselves. Have a great night.

Bob,
It is a pleasure to read all of these posts especially when working up loads for a new rifle in 7MM Rem Mag. Have some interesting data. Went to the range the other day and ran some Nosler 140 C-T's and RE22. I was a little shy about using a bunch of RE22 as my experience with another rifle (Mark X action and a 24" Douglas) made me that way. Couldn't put a tenth more in that one over 65.5g with a 145 Speer or the base of the brass would burnish @ 75 degrees.
Anyway here it is. RE22 140 Nosler C-T. CCI Mag Primers. W-W Brass. Bullets seated .020 off the lands.
67g 2931. 67.5g 2940. 68g 2986. 69g 3031.
Barrel was allowed to cool between shots and none of the powder charges gave any indication of being too much. Looks like another grain will yield close to 3100 so I thought RE19 may be the ticket and have loaded a few to test starting at 66g.
The barrel on this rifle is a Spencer and is not 25" as previously posted but 24 1/2" measured from the end of the threaded "tenon" to the muzzle. The throat is deep. A 150 Nosler BT seated @ 3.920" -.020" off (Comparitor)is at the bottom of the neck. A 140 Nosler (not a C-T) is too short to be gripped by .200" of the neck unless it is seated -.130" off.
140 C-T's, 150 Nosler and Sierra, 160 Speers are all OK as far as seating goes and these 7's will shoot about anything but I am a little miffed about the velocities I am seeing. Also, the chamber in this barrel won't accept a FL resized once fired brass shot in a different gun. I have nothing to bump the shoulder's with other than "over camming" the press.
150 Nosler's w/ 64.5g IMR 4831 are right at 3000 to 3040fps and shoot great. Tried adding with this combo and the group size doubled. What do you think about this deal and the velocities I am seeing. If anyone has any suggestions please do not hesitate.
Thanks,
Dave

RaceTire,

I think there's a typo re: the OAL of a 150 BT.....with the bullet seated to the base of the neck, it's around 3.536.

That's 1.307" for the bullet + 2.229" for the case length to the base of the neck.

I like to be in the range of .020"-.050" of the lands in hunting rifles......with the preference for the lower end of that range of it works.

In the 7mag, I've generally found that RL25, H4831 and IMR7828 are better than the slightly faster powders like 4350, IMR4831 and RL19 with bullets of 140 grains & up.......YMMV.

IMR4831 is an excellent powder and I'm suprised that your accuracy got worse by a factor of 2x with it above 3000 FPS....however as already said, it is not in my top tier of powders for the 7mag and that does happen sometimes with certain guns & powders.

I do have to say that my accuracy with 7828 has not been as good as with RL22 though.

As for sizing cases not fired in a given gun, and not fitting after FL resizing, I've had this happen on a couple of guns with SAAMI minimum or near minimum chamber.....it can happen.

Here's a link to something that might help...... no guarantees, but it's worked for me in the past.

Belted Magnum Collet Resizing Die

MM

MM,
Appreciate the input. My post was a little confusing regarding OAL as I did not make it clear regarding my use of a Stoney Point Comparitor and my use of the dimensions it produces. The true OAL of the loaded 150 Nosler BT in this rifle is 3.495" which is 3.920" when the comparitor is attached to the calipers.
I use what I call the "pushback" method along with the bullet blacking method to determine where the bullet hits the lands and can get pretty close. 3.920"/3.495" in my 7 is .020" off as best as I can determine.
I haven't worked with the IMR4831 enough to give it a good opportunity to give me the right velocity and good accuracy. Actually stumbled on to the 64.5g load in doing some load work and it is real accurate. Can probably add more powder to get the v up and work with bullet seating depth to get it as accurate as possible. Deal here is going to be to get it to shoot in the mid 2's (like it does @ 3000fps) which won't be easy.
Looks like it's going to take at least another grain of powder to yield 3100fps.
Thanks for the recommendation on the tools to help to get some of the brass I have to work.

Dave

Well, after two trips to the range with the 140TSXs, here's what I've found with my rifle:

1. Retumbo at around 3000-3025fps was very accurate. But I seen no advantave since I already shoot 160g North fork at that velocity.

2. H4831, H4350 and H1000 all got me 3150 to 3303 but accuracy was not what I wanted with any of them. H4831SC and H1000 showed promise but the second trip failed to verify anything but good velocity.

3. My conclusion is my rifle just doesn't care for the 140g TSXs, a surprise, because TSXs shoot well in my .257 Roberts, .308 Win, .30-06, and 300 Win Mag.

I'm going to try 140g North Fork bullets instead. If they don't work I'm going to stick with the tried and true 160s. Might just cut my losses and do that anyway.

Very interesting post Gents, wished I had seen the post earlier...was wondering the same about the 7RM and the Weatherby.

Bein old and grey I remember the fuss the 7RM brought about. Early on they actually chambered pretty deep expecting the belt to headspace. This made for some extra case capacity which we used with the old 4831. Mine was not so long throated but the best bullet we had at the time was the 175 grain Nosler partition and it was a semi-spitzer and I mean semi. It was a 2 inch rifle with this bullet but it killed well and penetrated really well. I would be surprised if I was getting 2900fps though. This rifle was a tackdriver with the 160 grain Sierra Gameking and with a max load of old 4831 this bullet was real hard on deer to way out there.

Very interesting what you have done with the barrels.

280Rem is right.
In the late 70's, a retired owner from Illinois of a tool and die company moved in on our road. His primary customer was Remington. He had access to Remnington's ballistics lab and showed me printouts of pressure curves of the 7RM--the first time I had seen or heard of such exotic stuff

He said back then Remington had been seeing some unpredictible pressure spikes they couldn't explain. Ultimately Remington reduced the charges in their factory loads in the late 70's and again in the early 80's. If you ever take a look at the old Remington brochures the advertised velocity of 150gr Core-lokts went from 3300fps in the 60's and eventually to 3110fps in the early 80's.

Maybe you discovered something, free bore and different lands may be a method to "circumvent" the pressure spikes.

Allegedly, Remington never had a definitive answer as to the why the pressure spikes were occurring.

Casey

Casey: Been going back and forth with Montana Man on this barrel issue and am presently working with a 9 twist Krieger 24" CM barrel on a M70 Classic action. The throat is on the long side, and the 160 NP is seated as long as a 30/06-length box will handle.I have so far worked with RL22,25,7828 and H4831; gradually working up and watching the chronograph, pressure signs, primer pockets, etc.

Best combo of accuracy and velocity has been 70 gr-H4831-160 NP for about 3100. I know this is over what the books call for, but so far primer pockets are tight on firing #3.

Curious thing about the load is this rifle demonstrates that peculiar characteristic of shooting only so-so at 100 and 200;but groups at 300-500 are hovering around MOA or less. I fired the other day at 300,400, and 500, and the biggest group was about 6" at 500 yards.Groups fired the day before were similar. Wish I knew the reaon for this. Boddington recently wrote in G&A that it's the crown....I don't know.

Casey: All this ballistic "gack"(as Dober would call it) over the 7 rem mag, and 30 years with the cartridge has led me to some conclusions(not that they count for much, and not to take away from the game-getter ability of the cartridge).

First, I think the Mashburn may have been optimum in terms of what a big 7 should do, but it's a wildcat.

The STW is great but requires a H&H-length action and seems to need a 26" barrel, which is sort-of a drawback.

The 7mm Dakota may be the best factory-produced big 7 of all time, but is proprietary and not commonly available.The 7mm Weatherby is simply the 7 Rem Mag with a long throat.

So, I want a 30/06 length big 7 with a tad more capacity than the Rem Mag, with industry-standard throat/leade dimensions,commonly available factory brass, and cabable of an honest 3150-3200 fps with a 160, and 3050-3100 with the 175,from a 24" barrel. This will still leave recoil a notch below the 300 mags,while providing all the ranging ability and lethal effect necessary for most game in most situations.I THINK, but don't know for sure (I am no ballistician)that the 375 Ruger necked to 7mm can provide this, which is why I want to see it standardized.

Till then I'll just wallow around with the 7 Rem Mag.

Talked to Mike at North Fork today and ordered some 140g bullets. He indicated he is changing the ogive on them (pending test results) to give them a higher BC.

Once I get them I'll repeat some of my tests with the TSX to see if I get better accuracy with the North Forks.

Still not sure why I'm doing this except that I shoot 165's in my .308 Win and .30-06 and 180's in my .300 Win Mag. The 140's, if I can get good accuracy at the velocities I want, would be my flattest shooter. The 160 North Forks give me a tad over 3000fps and .5" accuracy - I guess the 140's are just something to play with...


BobinNH -
I agree with you about the various 7mm's. Wanted a Dakota for some time and considered rechambering but there were issues with the bolt face, magazine capacity and so on that kept me from doing so. A .375 Ruger necked down to 7mm is the perfect solution. I think we'll see factory offerings of necked down .375 in several calibers over the next few years.

Bobo-the Mashburn is a wildcat??? grins

Dober

Dober: How can it be a wildcat?You make it, right?.....

Coyote: See no reason the North Fork should not be great, though I have yet to try them.GO RUGER!

Mark, How about a quick synopsis on the Mashburn. Have read about it in the past but was a while back and memory is a little fuzzy. I call it information overload.

I tried to google it. Find plenty of references to it, but no real info. Also saw a "7mm-06 Mashburn." Same or different cartridges? I thought the 7mmRM was Remmy's factory version of the Mashburn. Are the ballistics much different?