Home Forums Hunting & Shooting Ask The Gunwriters 30-06 +p with low temp sensitivity

Yes that was back in the early 70's. (Showing my age)
I wouldn't be surprised if the new copper bullets TSX etc, did penetrate as well at higher velocities. They penetrate much better in the classic calibers, at moderate velocities as well. If you can penetrate your deer from end to end, it doesn't really matter, unless you're concerned with (hydro) meat damage etc. All that extra energy isn't much use expended in a pine tree on the other side..
If I was really interested I would do the test again. I think the faster a bullet expands in tissue, the faster it slows down and the faster round may still penetrate less or at least no more. The fact it expands less, may or may not be a factor, I now use those TTSX (type) bullets in about everything, including my 7x57R drillings with great success. Calibers that I once considered poor for deer, like the 243, are much more acceptable with bullets that stay together and finish the job.

" Faster bullets can actually reduce penetration due to rapid premature expansion, as well as causing significant meat damage.
The 2 calibers were 7x57 Vs 7mm Rem Mag and 308 Win Vs the 300 Win Mag. Loaded to factory specs, using the same bullets. 139 & 180 gr. respectively.

.... as the standard calibers penetrated 25-30% deeper than the magnums." Brayhaven From P 5

I am still being polite.




It 'seems' to me you know Premiums penetrate 'farther' with higher velocity, no ?

Jerry

brayhaven,

No, Ackley did NOT use high-pressure .30-30 handloads in his tests. He used factory loads, as you'll find if you go back and read the test carefully. The rifle was rechambered for the .30-30 Improved during the test, but Ackley continued to use factory ammo. However, he did use heavy handloads in the .250 Savage, which is probably why a lot of people make the mistakes that the .30-30 ammo was handloaded.

But here's an article detailing why Ackley's test, and hence his conclusions, were flawed:

“Bolt thrust is the term used for how much pressure the head of a cartridge case imparts to whatever holds it inside the chamber. This can be a bolt, but it can also be the breech-block of a single-shot, the frame of a revolver, or the face of a break action.

However, the greatest bolt-thrust is created by modern rifle cartridges—along with the greatest misconceptions about bolt thrust. Since the firing of a cartridge shoves the case backwards, many shooters intuitively assume the case head creates the most pressure. They’re wrong, and the common ideas that case shape or chamber lubrication affect bolt thrust are also wrong.

These misconceptions probably arose from a book published in 1962 by famous gunsmith P.O. Ackley, entitled Handbook for Shooters and Reloaders. Ackley was a frequent experimenter, primarily remembered for “improving” factory cartridges with a 40-degree shoulder angle. This technique is so well-known that any improved round with a 40-degree shoulder is known as an Ackley Improved, even of P.O. Ackley never fooled with it.

One example is the .223 Remington Ackley Improved, which didn’t appear in the original Handbook because the .223 didn’t become a factory round until 1964. Fans call it the .223AI, with many claiming muzzle velocities close to the .22-250, especially with 40-grain bullets.

The maximum velocities listed with 40’s for the standard .223 in handloading manuals run around 3800 fps, but .223 AI enthusiasts often report velocities of 4000-4100 fps, an increase of 5-8%. One basic rule of interior ballistics is that potential muzzle velocity in any given caliber is ¼ any increase or decrease in case capacity—if both cartridges are loaded to the same pressure. (I derived this rule empirically from loading data. It’s since been basically confirmed by people who know a lot more about physics.)

According to the 4-to-1 Rule, an increase of 5-8% in muzzle velocity implies an increase of 20% to 32% in case capacity. I just measured the water capacity of a once-fired “standard” .223 Remington case with a Berger 40-grain hollow-point seated to the maximum SAAMI overall length of 2.26 inches. (This is the correct way to measure case capacity, not filling the case to the mouth, since the necks of cases are partially or totally filled with bullets, not powder. A fired case should be used, since new cases hold less water, often much less.) The result was 30.6 grains.

A 20% increase in velocity implies a case holding about 36.7 grains of water, 6.1 more grains than the standard .223 case—a remarkable amount of “improvement,” since the popular.257 Roberts Ackley Improved only gains about five grains over the standard .257 Roberts in a much larger case. A 32% increase in powder capacity would mean a case holding 40.4 grains of water, and the .22-250 only holds around 42-43 grains of water with a 40-grain bullet seated, depending on the brass.

In the real world, of course, the .223 AI doesn’t gain nearly that much powder room. A friend who’s a .223 AI fan was kind enough to give me a formed case, which holds not quite two grains more water with the same Berger bullet seated to the same depth. This is about 6% more than the standard .223 case, and according to the 4-to-1 rule means about a 60 fps increase in potential velocity.

So how does the .223 AI get over 4000 fps with a 40-grain bullet? I discussed this problem with another .223 AI enthusiast, who claimed the reason was the case shape, since less body taper results in less bolt thrust. Upon further questioning, he said P.O. Ackley proved this years ago, in his book.

That evening I dragged out my Handbook, so old and well-read the spine is held together by duct tape, and re-read the chapter on pressure, where Ackley states: “Wildcatters feel that minimum body taper design reduces bolt thrust. This theory tends to be substantiated by results.”

First he describes locking up a Savage 99 in .250-3000 (a very tapered case) by firing a fairly warm powder charge with a 100-grain bullet. When the same rifle was rechambered to an improved version of the .250 with very little case taper, cartridges loaded with the same charge and bullet extracted easily. The improved cases could then be loaded even hotter, but the action wouldn’t lock up.

He next described experiments with an old Model 94 Winchester rechambered to an improved version of the .30-30. Ackley first unscrewed the barrel one thread, whereupon the primers backed out but the case remained in the chamber. He then oiled the case to see what would happen, and upon firing it backed out of the chamber. The same experiment was then repeated with the barrel unscrewed two threads, and the same thing happened. Finally he removed the locking lug and fired the rifle by holding the action closed with finger-pressure, and the case didn’t back out.

Ackley said “the tests described seem to indicate a very small percentage of the CHAMBER pressure was transferred to the breech bolt in the form of thrust,” and claimed they offered proof that case shape has a large effect on bolt thrust. He was wrong.

First let’s look at Ackley’s “experiments” with the .250-3000 in the 99 Savage. I personally did a bunch of experimenting with overloads in the .250 Savage case back when I was younger and dumber, by trying to turn it into a .257 Roberts by adding powder. The rifles were several Savage 99’s, plus a Remington 700, Ruger 77 and Winchester Model 70. The 99s would stick even when the round was relatively lightly over-loaded (if “lightly” can be used in that context), but none of the bolt actions ever required any extra effort in opening the bolt when using loads that would lock up a 99, so something else was causing the problem.

a rear-locking bolt like the one on a 99 compresses significantly when firing an over-pressure round , unlike the front-locking bolt of a 700, 77 or 70. [You can find this information in Otteson's book THE BOLT ACTION.] Any case will back out of the chamber slightly when that happens, and also lengthens slightly due to fire-forming. When the compressed bolt decompresses, the tapered, lengthened .250 case then wedges firmly into the chamber. With the minimally tapered .250 Improved, the case also backs out and lengthens slightly when fired with an overload, but due to the minimal taper and sharper shoulder, doesn’t wedge in the chamber like the standard .250 case. Or at least that seems to be the most reasonable explanation, given the evidence.

As for the .30-30 experiments, Ackley only fired the rifle with factory loads, and the SAAMI maximum pressure for the .30-30 is 42,000 psi. To understand why this experiment doesn’t demonstrate anything about bolt thrust, we need to understand that at a certain pressure, not far above the .30-30's 42,000 PSI, brass cases stretch enough for the case head to press firmly against the bolt face. This is why primers will often be backed out of .30-30 cases slightly after firing, but not .30-06 cases: The .30-06 cases stretch to press firmly against the bolt face.

This indicates that the "yield strength" of cartridge brass is somewhere between 42,000 PSI and the 60,000 PSI of .30-06 factory ammo. Cartridge cases work-harden while being formed in dies during manufacture. The thin neck and shoulder are annealed afterward, so they’ll stretch without cracking, but the case heads are left hardened so they won’t deform or break easily. As a result some primer pockets don’t permanently expand until pressure is over 65,000 psi.

However, even unhardened cartridge brass will withstand 15,000 psi more than the maximum average pressure of a factory .30-30 round. This is exactly why the primers backed out of the factory .30-30 loads in Ackley’s experiment, instead of the case stretching to fit the lengthened chamber. In fact it’s common for primers to back out of cases in lower-pressure cartridges fired in worn lever-actions. I have a Winchester Model 1894 rifle in .25-35 made in 1898, and the primers on factory ammo back out very slightly when fired. In either instance, there’s zero bolt thrust—and the .25-35 cases fired in my rifle aren’t “improved."

The fact that the rifle could be fired safely merely by holding the lever closed doesn’t prove anything about the .30-30 Ackley Improved. The rifle probably would have done the same thing without being rechambered, but Ackley didn’t try it.

The notion that oiling the case results in greater bolt thrust is also faulty, because even the heaviest greases with “extreme pressure” additives don’t retain lubricity above 10,000 psi. Yes, a lubed case with excess headspace will slide back against the bolt face when fired, but once pressures rise above 10,000 psi the case sticks to the chamber.

In the same chapter there’s also a quote from Vernon Speer explaining why the Speer lab used measurement of case-head expansion (CHE) for working up handloads for their manuals. He claimed CHE was more accurate than the copper-crusher pressure guns used in those days, but lab technicians I’ve interviewed say copper-crusher testing can be quite accurate, as long as painstaking measurements are made. The reason it’s not used much anymore is electronic testing doesn’t require nearly as many measurements, so is much faster. Some handloaders still believe in measuring CHE today, when electronic pressure guns and strain-gauges have proven the technique isn’t reliable.

In fact, thanks to technological progress there’s even a way to measure bolt-thrust through highly sensitive films. Charlie Sisk, the Texas gunsmith, has been performing experiments with the Pressure Trace strain-gauge system for a number of years now, and eventually became intrigued with bolt-thrust. He used the Topaq computer services of Sensor Products Inc. to analyze the pressure between the bolt face and case heads in cartridges from the .223 Remington to the .300 Winchester Magnum—including the .22-250, based on the very tapered .250-3000 case.

Sisk applied pressure-sensitive Fujifilm to the heads of the cases, then fired them on his indoor range and sent the cases to Sensor for analysis. The results repeatedly demonstrated that the pressures created by modern bolt-action cartridges (not 1890’s lever-action cartridges), press the heads of cases against the bolt-face with exactly the same pounds-per-square-inch as the rest of the chamber, regardless of case shape.

This isn’t exactly startling news. Ballistic engineers have known it for a long time, but most engineers don’t write popular handloading books. So what’s the source of the magic in the .223 Remington Ackley Improved? I’d long had my own theory, so tested it by handloading some once-fired Winchester-brand .223 cases with deliberate overloads, using Ramshot TAC powder and 40-grain Berger Match Varmint hollow-point bullets.

TAC was used because it’s a fine-grained ball powder, so more will fit in a case than some other top .223 powders such as Hodgdon Benchmark. The Berger bullet was chosen because Ramshot’s on-line data showed a maximum load of 27.3 grains of TAC at 54,170 psi, just below the maximum average SAAMI pressure of 55,000 psi for the .223 Remington.

I started with 29.0 grains of powder, working up in half-grain increments to 32.0 grains, stopping there only because 32.0 grains was all the TAC I could get in the cases, even when tapping the funnel while very slowly dripping the powder into the necks. Then I fired the loads on a 70-degree day in a Thompson/Center Icon with a 22-inch barrel, chronographing the velocity with an Oehler 35P:

29.0 grains—3658 fps
29.5 grains—3759 fps
30.0 grains—3849 fps
30.5 grains—3946 fps
31.0 grains—3997 fps
31.5 grains—4014 fps
32.0 grains—4025 fps

No traditional sign of high pressure showed up until the 31.0 grain load, when bolt-lift became a little stiff and two case-heads showed a slight ejector-hole mark . At 32.0 grains all the cases had definite ejector-hole marks, and lifting the bolt required considerable effort. In fact on two cases the bolt handle had to be tapped open with a wooden hammer-handle. Also, note that velocity increases were also much smaller in the loads over 30.5 grains.
I then tried the 30.5 grain load in a Remington 700 with a 26-inch barrel. The muzzle velocity was 4046 fps, and there were zero signs of high pressure. Adding the 60 fps from the 4-to-1 Rule would result in the muzzle velocities many .223 AI fans report.

Obviously, the 30.5 grain handload produces far more pressure than the 27.3 grain maximum in Ramshot’s data. I didn’t have the load pressure-tested by either Western Powders or Charlie Sisk, but according to one of Homer Powley’s formulas the pressure would be at least 65,000 psi, 10,000 psi over the SAAMI limit for the .223 Remington.

Are such loads safe? Obviously, SAAMI’s maximum .223 pressure of 55,000 psi is lower than the yield strength of even unhardened cartridge brass. It’s also obvious that some handloaders have been firing .223 AI handloads at much higher pressures for a long time. A smaller case-head produces less bolt-thrust, due to less area pushing against the bolt’s face, so maybe they’re safe, but the velocities they’re getting aren’t due to the magic of an “improved” case. Instead they come from the tradition of working up wildcat handloads until the rifle and brass show signs of distress, then backing off slightly. The result is extra pressure and extra velocity. It’s that simple."

After this article was published, I was contacted by two different engineers who objected to the proof of the Fujifilm pressure tape, mostly because they had swallowed Ackley's "evidence" years ago. One insisted the results with the film were flawed because the headspace in the test rifles was too minimal, compressing the tape. The other engineer insisted the headspace was obviously too much. Which just proves the old definition of two engineers in a room is "an argument." Neither one could provide any evidence to contradict the results of the tests.

Also post-publication, I discovered why the .223 was once reported as producing velocities almost as high as the .22-250 with far less case capacity. It turned out a major bullet company came to that conclusion after strain gauge tests of the .223 AI, where velocity were very high but pressures in the 60,000 PSI range.

But apparently, the person who ran the tests didn't understand that strain-gauge pressures run somewhat lower than piezo-electronic pressures. When the same .223 ammo was retested in a piezo lab later, the magic velocities of the .223 AI disappeated--because they were due to much higher pressure than 60,000 PSI.

My experience has been quite different from that treatise. I've seen a lot of 30/06 and similar cartridges back the primers out with excess headspace in blot action rifles. And the fact that he was using factory loads in the 30/30 AI using the AI chamber didn't change his often proven statement. As soon as the cartridge expanded to the near straight walls of the chamber it no longer went backward.
The AI loads he published were much higher than the 42K pressure. I chambered a Ruger #1 for it and pushed his loads a little higher still. I used the 3200 fps 110 grain load in a Marlin 336 I chambered, for prairie dog hunting. It would blow a primer pocket on occasion in the sun.

Also, I disagree with his claim that lubing a case will not make it thrust rearward. I've had many customers over the years just do that with their guns with headspace. Lubing the cases, moved the shoulder forward and took care of the problem. Just had to back up the sizing die a bit. The fact that excess headspace will back a primer out against the bolt fact on any rifle, is proof that there is relatively little bolt thrust except in a lubed chamber & case. Then the primer stays flush, and the shoulder is moved forward as the case moves back against the bolt face on firing.

That's my experience with it. Many of the AI rounds weren't much of an improvement, but some including the 30/30 definitely were. The so called .223 improved wasn't much better than the original round.

So Mule Deer, since so many have been running the 223AI at obviously "high" pressures for so long with absolutely no problems, is there any reason not to push the pressures up that high?

brayhaven,

Ackley never fired factory .30-30 loads in a STANDARD chamber with exceess headspace, so we have no comparison about how they might have backed up either. But I have seen it hundreds of times when shooting various low-pressure cartridges from the .25-20 to .348 Winchester.

I have yet to see a .30-06 (or similar pressure cartridge) leave primers backed out with normal pressures. They will with "starting" or reduced loads, but there isn't a .30-06 case made that won't stretch enough to back over the primer at normal pressures. In fact I have thousands of fired factory cases from higher-pressure ammo in my shop, and none show backed-out primers. The ONLY ones that do are .25-20's, 25-35's, .30-30's, American 8x57's and similar low-pressure rounds.

In fact, that's the very reason "flattened" primers aren't always an indication of excessive pressure, as so many assume. When a high pressure (say 55,000 PSI) round is fired in a chamber with a little extra headspace, the primer backs out and, if pressures are high enough, expands slightly, because it's no longer supported by the primer pocket.But then the case backs up over the expanded primer, "flattening" it, even when pressures are normal.

Please note that the mention of lubed cases not expanded to fill the chamber specifically applied to SOME oils, not all.

The experiments with bolt-face pressures in the article were repeated many times, with cases of various shapes, and the result was always the same, no matter the case shape.

But apparently you made up your mind about all of this a long time ago.

DakotaDeer,

The standard SAAMI maximum average pressure (MAP) for the .223 is only 55,000 PSI, when many modern rounds have MAPs of 60-65,000 PSI. The so-called "pressure" signs used by many handloaders such as primer pockets expanding, difficult bolt lift, and ejector-hole marks on the case head usually don't show up until pressures are above 65,000 PSI, and with some brass well above 70,000 PSI. So there's at least 10,000 PSI and sometimes 20,000 to play with above standard .223 pressures.

Apparently the reason for the 55,000 PSI MAP is reliable performance in autoloaders, though 5.56 NATO ammo, as I recall, is loaded to over 60,000 PSI. And two cartridges on the same case-head have much higher MAPs, the .221 Fireball at 60,000 PSI and the .17 Remington at 63,000. I don't see why loading .223 ammo to 60,000+ PSI would be a problem, bu conditions such as temperature, whether ambient or a hot barrel, can change pressure considerably. Which is why it's probably not smart to really push the envelope, whether with the standard .223 or the AI version.

No I didn't "make up my mind". I just gave you my first hand experience, based on 45 years of gunsmithing. I've seen many 06, 270, and a lot of military rifles with excess headspace that back out primers with factory loads.
I suspect those bolt face pressures would have been because of momentary head pressure & bounce back. Most likely with minimum headspace. And shooting a factory round in a AI 30/30 chamber with no locking lugs, shows very little breech pressure occurred. It should have been greater (with an unformed case), due to the case having to expand into the chamber before moving to the rear. If the pressure on the bolt face was equal to the chamber walls, it probably would have taken his thumb off.

As an infantry officer in the late 60's I taught maint & operation of the Browning 50. I could always tell when the operator hadn't set the headspace correctly by looking at the fired cases on the range next to his gun. The primers were backed out a few thousandths.

But apparently my experiences, and those of my many gun maker mentors over the years, differ from yours. That's fine too.

"And shooting a factory round in a AI 30/30 chamber with no locking lugs, shows very little breech pressure occurred. It should have been greater (with an unformed case), due to the case having to expand into the chamber before moving to the rear."

This sounds like you're saying the pressure from a factory .30-30 round in the AI chamber should be greater than when the ssame ammos' fired in a standard chamber. Is that actually what you're claiming?

I can see primers backing out of a .50 BMG case because the brass is so thick it resists stretching. Have seen the same thing with other cartridges using very thick brass, including the WSSM's and .338 Lapua.

But in standard commercial cartridges like the .270 I have yet to see it--with one exception. I'm often sent rifles ammo for test reports in various magazines. Consequently I have a bunch of .270 factory ammo on hand, the brands including not just the usual Federal, Remington and Winchester, but Hornady, Norma, RWS and a couple of small makers. In most of those brands there's more than one load. Since January of 2014 I've fired the ammo in four of my own .270's and five others, made both in America and Europe, so they could be assumed to have slightly varying headspace.

I just checked the fired cases remaining in the boxes and none have primers backed out--EXCEPT some Hornady Custom Lite ammo loaded with 120-grain SST's at a listed 2675 fps, obviously a reduced load. The primers in these were backed out anywhere from .003" to .007". The lack of backed-out primers in the full-power ammo, fired in various rifles, does seem to be contrary to your experience.

Interested to hear from the GWs, ballisticians and tinkerers re R17 a little more.

Yes there's been lots of debate about its magicness or otherwise. But geez, in just about any cartridge you want to name in the 4350 burn rate bracket, R17 seems to top the Quickload data, with higher speed or similar speed at lower pressure.

The above mentioned 30-06 pressure charts run by Kocur at the Mulwala plant further boost the claims of R17. In all those tests, R17 produced more speed at lower pressure or at worst the same speed at less pressure than H4350, H4831SC and R22, with 180 and 200g bullets.

With 200g bullets, R17 produced the same speed as R22, with slightly less pressure, with 6 grains less powder. Just over 2700fps at under 62k psi. I think that's impressive.

I've come pretty late to the R17 party, I usually stick with the ADI stuff. But as a sub for anything in the Varget to H4831 burn rate I've struck fast speeds and great accuracy.

I'm happy to be shot down in flames, but it really does seem to me that R17 does things in that burn bracket that few others do. Perhaps it's less magic and just normal evolution of propellant technology.

Any thoughts?

I've seen reports of that test being done, but lots of folks promote incorrect ideas in all fields, including scientific ones, that get accepted by the mainstream.

I'm not familiar with Ackley's educational background, but it seems that having even a few basic Physics courses under the belt would show the difference between assumptions and conclusions, and the errors in that conclusion should be evident.

I think Ackley had a problem with basic measurement that he made up for with enthusiasm.

And yet...

Many kudos to him for his pioneering efforts!

Quickload is modeling software that makes speculations about interior ballistics, and R17 uses a different set of definitions that affects the algorithm differently...that's all.

R17 has a slightly higher energy density than 4350 due to the added nitro content, but a similar burn rate, so it's easier to fit more of it into a smaller case...therein lies the magic.

Excessive headspace causes primers to back out during the early stages of combustion, but that has nothing to do with development of peak chamber pressure that occurs later in the cycle.

Also, during a MG firing sequence, different pressures are applied to a case that is in different places relative to the chamber at different times...again, none of those factors have anything to do with peak chamber pressure.

Its certainly quite good at getting a fair bit into a case. I'm even using it in the 308 with great results and I'd have thought it too fast for that.

The apples to apples tests by Kocur against the H powders were the ones that really caught my eye, even though its just a narrow range of application ie 30-06 with 180-200g bullets.

Bob - that's interesting. Do you normally use powders that are 'slower burning' than 4350 in the 308 ?

It's been a long time since I had and loaded for the 308, but I never used powders that S burning. BUT I didn't load heavier than 150s.

Jerry

At present I'm loading the 168g Amax with 49g of R17; 2820fps in a 26 inch barrel. 49.5 gave 2890fps but I backed off. From memory I think about 50g is the max in the Alliant book. Its running around 0.75moa for three shot groups and I'm not much of a bench shooter.

To answer your question Jerry, no I would normally go no slower than Varget but as I saw one of the guys on here (maybe Montana Marine) getting rave results with R17 I thought I'd try it.

Going to try R17 with some 155g bullets next. It *may* be a little slow for those weights but we'll see.

I should add the correction that Alliant lists a max of 50g with the 165g Speer BTSP with R17, not the 168g Amax I am using.

Bob, IMO that ain't bad for 168s in a 308.

Jerry

I don't know what Ackley's educational background was either. Likely the school of hard knocks. But many of his conclusions were based on actual testing, "trial & error" and results rather than "enthusiasm" or theories. He did differentiate between breech and chamber pressure, the former of which is variable with case design, brass strength, and chamber conditions. But you're right that a lot of things become accepted as facts because they're on the web or published in one of the gun rags, that are rubbish. Some of the gun nonsense I read online makes me laugh out loud and shake my head. Seems to be about as much misinformation as information.

"It doesn’t matter how beautiful your theory is, it doesn’t matter how smart you are. If it doesn’t agree with experiment, it’s wrong." Nobel physicist Richard Feynman