Home Forums Hunting & Shooting Custom Rifles & Wildcats Interesting thread on the short mags..........

Mule Deer's right... my 300 WSM, with max loads and the bullet seated for an OAL of 2.820" still has more room for powder... what's the worry about seating the bullets deeply if there's even more room for powder...???

BA

Chuck.....you missed my point. Both of my Lazzeroni cartridges are "short" in fact they are shorter than either the WSM and SAUM. They are, however, fatter and they do hold less powder than either the 300 Win Mag and 375 H&H.

I do believe the concept of more efficient burning of the powder takes place so less powder can produce similar velocities if used efficiently.

Mule Deer

I know where Rossi got his info re: Remington's UCL bullet. It was from JRS your fellow scribe at Rifleshooter. I read the same article where JRS said that was how the SAUM for same weight bullets could equal the WSM velocities with 5% or thereabouts lesser case capacity. (ie. he referred to 'smoke & mirrors' if I recall correctly as Rem used the shorter UCL bullet & Winchester used the Failsafes which are longer to achieve nearly identical velocities).

Very interested that you have debunked this seating depth issue as a myth. Be very interested to read your article when it is published. BTW really enjoyed "Optics for the Hunter". Helped a lot in making my choices & learnt to test things myself rather than take what some old Pro said about Kahles or Pecar scopes' light gathering ability. Again some myths there.

I was really taken aback by your comments on the 7mm Rem. I have just started to reload for it. Can you please elaborate on these 8,000 psi spikes. Is it only an issue with certain powders only (I'm using AR2217 also known as H1000) or an issue with the cartridge generally.

I have not heard that the 7mm Rem was anything other than "reloader friendly"? We amateurs have no way to reliably measure pressure so we have to rely on the professionals to publish the correct information.

Regards,
JohnT

The pressure spikes with the 7mm Remington Magnum do tend to occur with some powders more than others, but it's a problem in general.

Many shooters on this forum probably don't remember (or weren't born) when the round first came out in 1962, but the original factory ballistics were 3260 with 150's and 3070 with 175's, velocities that are barely exceeded by the 7mm STW today. Of course in those days few hunters owned chronographs, but independent tests showed Remington came pretty close, especially in the 26" barrels standard for factory testing back then. This was with IMR7828, which was developed for the cartridge. The round was hailed as the new Wonder Cartridge of the century.

The pressure spikes weren't discovered until the industry changed from copper-crusher pressure testing to the more senistive piezo-electric method. The standard SAAMI max velocities were then dropped to where they are today, 3110 with 150's and 2860 with 175's. These are taken in 24" barrels. They will still do any job that needs doing but are a long way from the original specs.

The data in loading manuals reflects this. Any pressure-tested loading data takes into account pressure swings, the reason you never see pressures of any load right up at the maximum SAAMI limit for ANY cartridge. This is why the max average SAAMI standard for the 7mm Rem. is only 61,000 psi, as compared to around 64-65,000 for most other magnums. If you stick to published load data and don't try to turn your 7mm Remington Magnum into a 7mm STW you'll be fine.

The same phenomenon occurs with the .243 Winchester and 100-grain bullets, though not with varmint-weight bullets for some reason. This is why the .243's factory velocities are so much lower than the 6mm Remington's even though there isn't that much difference in the case capacity. The .243's original factory velocities were also dropped considerably when piezo equipment became common.

This comment on the 7 mm Rem Mag being a "touchy" cartridge leaves me with doubts. If it is so I would like to know why? There are some ballistic experts on this internet including Ken Howell and maybe others and I would like to hear how and why.

My experiance with the 7mm Rem Mag is long but narrow. I got one soon after they came out and I loaded it to it's max and I have the chronograph and head expansion data to this day. Then I got another one in 1969 and shot it until the barrel wore out. Almost all of this shooting was done with the keg of surplus 4831, various primers and conventional bullets. Never did I see any pressure spike.

I don't see the 7mm Rem Mag as being any different that many other cartridges like it. It's not overbore capacity nor is it a pioneer in it's general expansion ratio or other aspects.

Another smith has written that he has seen more blow ups with the 243 Winchester than any other. Again he was not specific however on that cartridge I have read that some necks have been thick enough to interfere with some tight chambers.

I am willing to learn something new every day. Most of us ask why when we hear something.

If the resonse is "It's one of those unexplained mysteries" then I have even more doubts and I am capable of getting scientific. To lead this in that direction I offer a fact from the field from mechanical failures. "The most common cause of mechanical failure is improper assembly"

While that seems general it's an effort to narrow this down.

JRS is one of the True Believers in seating bullets out. In fact, I believe he built a .300 WSM on a Ruger 77 '06-length action before the factory rifles were even out, so he could "seat the bullet out to the lands." If his gunsmith used a factory reamer, JRS was in for a surprise, as the lands in the .300 WSM start right in front of the chamber. There is no "throat" as we tend to define it.

This whole thing happened already. When the .284 cam eout a bunch of gun writers got incensed that it wasn't chambered in the Model 70 Winchester so the bullets "could be seated out where they out to be." Several built .284s on various '06-length actions at great expense, when they could have just gone down to the local store and purchased a .270--the cartridge the .284 was supposed to duplicate in short actions.

My piece on deep-seating bullets wil appear in HANDLOADER in a month or so.

I got the information about the 7mm Remington Magnum from the ballistics boys while touring the facilities of two companies, one a powder company and the other one of the Big Three ammo companies. The phenomenon is well known in the business.

You're not going to see it in the average rifle with published data, because they've made sure you'll be well below any pressure level where a problem might occur. I got the info about the .243 from the same sources. I've since talked to ballisticians from other companies who confirmed the information about both rounds.

If you want, go ahead and call a few of them. If you can find a copy, you might also check out A-Square's loading manual and the pressure spreads with the 7mm Remington. That manual is one of the few public sources that quotes pressure spreads along with average pressure.

None of the professional ballisticians I've talked to has any firm explanation of the phenomenon, though some think it's related to the angle of the shoulder and short necks. But nobody has any proof. By the way, I've talked to enough of these folks to know that there are some things they CAN'T explain. In fact, most labs talk back and forth a lot when they run into problems, helping each other out. They're all gun nuts to one degree or another!

Mule Deer.....the "problem" of short cases and seating depths is something that a lot of folks seem to have a problem with and I look forward to a full article on it but I recall you writing clearly about this non-problem on more than one ocassion.

I guess if Jack O'Connor didn't say it it can't be true. <img src="/ubbthreads/images/graemlins/wink.gif" alt="" />

Another touchy cartridge is it's 1/2mm skinner cousin,the 264.I find it is interesting the why of the downloading ,better measuring.

And the answer once again is....

.270/.30-06! Tall and straight like Gary Cooper. They feed well, shoot well and don't kick to speak of. Bullets do not protrude into the powder space but conversely can be seated out to reach the lands in SAAMI spec chambered rifles. They offer no reloading surprises. They are within an inch of anything's trajectory within the ranges where 99.347% of all game is shot, and are within 3 inches of anything's trajectory within the ranges wherein 99.752% of game is shot. They just get the job done with a minimum of fuss. Ta-daaa!

I know, I know - Bore-reeng.


Sorry, just being a smug smart-a**. <img src="/ubbthreads/images/graemlins/wink.gif" alt="" />

Mule Deer- Like JRS, I too, built a 300wsm on a Ruger long action as soon as reamers became available. I had it throated long and tight. Using Re-22 (I am at my office and do not recall how many grains), Fed 215 and Barnes 180xlc seated to 3.15 oal, I get 3125fps. Barrel is 25". Load is near max, but as some of my cases have 11 loads through them without problem, I don't think I am skating on too thin ice. I do wish I had a means of measuring actual pressure. I am not capable of doing case head measurement with any accuracy. I could measure the same head 10 times, in the same place, and get 10 different readings. I know it wouldn't measure actual pressure, but if I could get it to work, it could help see somewhat where I am.

Jim, you might not have too much of a future in firearms sales <img src="/ubbthreads/images/graemlins/grin.gif" alt="" />

Personally, I view the short magnums as nothing more than a marketing idea. Lets face it, the manufacturers need things to sell. They are in the selling business not the "gun" business. They constantly need different products to crow about in the gun rags to keep their business viable. I have never shot one of the new short mags and frankly, don't particularly care if I do. Reduce the action length by about half an inch and save 4 ounces. The gun should recoil more, right ? Sure it should. Add more powder to the case and the gun should recoil more right? Sure it should. Speed the bullet up and gun should recoil more right? Sure it should. What the heck have you gained here except marginal increases in bullet speed at the cost of more recoil? Now make the gun lighter and you get even more recoil with virtually the same velocity as the old 270 Winchester. I am getting velocities similar to what John B. reported in his article about the 270 short mag out of my old 270 Winchester ! Perhaps one might get just a smidgen better downrange ballistics due to 100 fps additional velocity but even most of this will be in your imagination and not a realistic advantage under field shooting conditions. Gimmie a break, here guys. No sir ree Bob, a marketing ploy. I'll keep my old 270 Winchesters. By the way, John, I enjoyed your article on the 270 short mags. Very informative.

We cannot see in to that violent explosion that occurs on ignition in the 7 Rem Mag or any other cartridge so the cause may not be verifiable but the resulting pressure spike is. When this many say so and do not say it about other cartridges, I listen just as they, also know some powders produce spiking they cannot yet understand. It continues to be one of my favorites regardless.

Feedback like this when it's does not come with numbers, dates and specifics is hot stove fuel and very interesting that it is.

I could point out that the 7mm Rem Mag and the 243 Win have short necks and that the heavy bullets protrude way into the powder space and then we would be chasing our tails.

I have worn the barrels out on 243's but all with varmint bullets so again I can't report any pressure spike with those loads. Also my 7mm Mags were shot with very few 160 SBT's and none longer.

I have a friend who is engineering mgr of one of the worlds biggest mfg companies. He does not put up with mysteries well.

However he has not figured everything out either. It's just that he and I believe that there is a specific answer for it and that's if the problem were even well defined here which it is not.

Here is a link to the scientific method http://phyun5.ucr.edu/~wudka/Physics7/Notes_www/node5.html

I offer this only in good humor and ask for instance for more data. For instance do the pressure spikes occur only with long bullets in the 7 mm Rem Mag?

Mule Deer

Thanks very much for that additional info. Geez you learn an awful lot on this forum.

Unfortunately, I gave up my subscription tn Handloader & only subscribe to Rifle now. Which issue no# will it be & I will get a friend in US to buy the issue.

I never saw velocities as high as that for the 175gn for the 7mm Rem. And you are right I was still in daipers then. My rifle is a Ruger No. 1 with a 26 inch barrel & I have no difficulties getting chronographed velocities the same or slightly more than published. So I don't tend to push it as everyone's opinions on pressure signs vary so much. Also I have read an interesting article where the really useful gains in velocity in "improved" cartridges and wildcats were due to loading to higher pressures than base cartridge. ie. no free lunch, you need cubic capacity.

Speaking of factory ballistics though, I do have an issue with the Win Supreme 270gn Failsafe .375 H&H ammo. Out of a 24 inch barrel it only chronographs 2550 not the 2700fps claimed. It does slightly less in a friends 23 inch barrelled Ruger. Is this being downloaded for safety reasons as well?

JB's point on the 7 Rem mag is hardly new news. There is a reference to this in Speer #13 (pub 1998) I can also recall mentions of this going back well before that.

Many of us "want" our favorite rifles or cartridges to deliver some arbitrary velocity that we set our hearts on. This is of course especially true with wildcats. (Rember the 7-08 AI thread).

With this goal in the back of our heads we go out and load it till we get there. Our chronographs say the right thing, our rifles "ain't blowed up yet" and we are happy. But we really don't know the pressures, and our best amateur efforts at pressure guessing are wildly innacurate at the best of times. Hence IMO, when the powder companies and loading manual publishers (who DO test pressures) back off on a cartridge, it's usually for a good reason.

For whatever the reason, the evidence seems to be out there and well established on the 7 mag and the 243. We amateurs would be well advised to err on the side of caution.

(Nobody has ever been able to quantify the exact reason for "fast or slow" barrels, but we all know that the phenomenon exists)

JimF

Rolly,

To paraphrase the good Dr:

Point 1: Some poeple will always jump on the bandwagon of anything that is the latest and greatest. I think they are seduced by the "hype".

Point 2: Some people will turn up their noses at the "hype" and stick with what has always worked. Porbably because it is "proven"

Point 3: Some folks are always looking for new things to experiment with. (That would be me)

Point 4: Classics have a way of coming back around when you least expect them. (Good things refuse to die)

Point 5: Some people will be attracted to anything just because it's "different".


Personally I think the WSM's and the RSAUM's are a passing fad. Probably the "ultra's" too. I will make a non-scientific prediction. I think the Remington SAUM will die on the vine. I think the .300 WSM will be around for a long time, and probably the .270 WSM to a lesser extent. I think the 7mm WSM will probably die a slow death, and that is sad because it is probably the best and most useful of the bunch.

The Rem. Ultra Mags? I don't think they will ever achieve more than a niche. Probably long after I'm history, hunters will still be confidently taking game with the .30-06, .270 Win. and .300 Win Mag. <img src="/ubbthreads/images/graemlins/smirk.gif" alt="" /> Cheers - the9.3Guy!

Don,
I do not have a clue. If it is random and cannot be consistently reproduced in the lab, then it is speculation as to what is causing the spike. I have read this about these 2 cartridges for some time. Since I like and have used the the cartridge so much, I would like an answer myself.

9.3,

I too think the RSAUMs will pass away. One or two WSMs are likely to fill a niche, and I think the 300 and 338 RUMs will last.

Blaine