Bullet weight and cartridge pressure sensitivities for other rounds

[BattleRifleG3]

I'm aware that the M1 Garand has certain sensitivities to loads and bullet weights, specifically that commercial hunting ammo should not be used and that bullet weights should be in the 150gr range.

I was wondering whether M1 Garands in 308 or other rounds had the same sensitivities, and if so what they were?

[Gyrene]

BattleRifleG3 - There are a couple of things that make the M1 Garand sensitive to loadings.

First, is the timing of the whole system to pressure peaks. IMR 4895 powder was designed to optimize the performance, of the M1 Garand, and while some are close, IMR 4895 has a burn rate and pressure peak that is virtually perfect for the M1 Garand, (and excellent for many other rifles of various calibers).

Secondly, the correct powder must be combined with the correct bullet weight (keep the bullet weight at or under 180 grains, and it should be OK as long as the Operating Rod Spring is a standard issue one). The M1 Ball Ammo which should never be used in the M1 Garand has a different powder, and too high a bullet weight. M1 Ball was designed for volley fire with the 1903 Springfield (and 1903 Rock Island) out to over 2,000 yards (and to 2,500 yards in the Browning .30 Cal machine guns). When it was found that repeatedly firing M1 Ball ammo in the M1 Garand, several things happened to destruct the rifle. The timing of the pressure peak was such that it slammed the operating rod so hard that it often broke after repeated firing, and at least one sent part of the operating rod into the face of the shooter. Replacing the operating rod when it bent or broke would eventually cause the receiver to break from the repeated impact of the bolt. This is the reason that M2 Ball was developed, and became the issue round for the M1 Garand. Remember that M1 Ball was still in the logistics system, and it was used for machine guns and 1903/1903A3's only.

An aside! The Johnson Semi Automatic Rifle (SAR) could fire either M1 Ball or M2 Ball. More than that, you could change to 7 x 57mm Mauser, or 7.92 x 57mm (8mm) Mauser, 7.5 Jap or NATO 7.62 x 51mm, or even the .308, with the Johnson simply by changing the barrel, which takes about 15 to 30 seconds (depending upon the skill of the operator).

Third, the military brass and primers are thicker than the commercial brass and primers resulting in a slightly smaller inside volume of the cartridge. Two things are important here, the peak pressure and timing are affected by the difference in the volume (it is a very slight difference, and I don't fully understand the interior ballistics, but when the pressure builds up in a larger or smaller space, timing is off, and peak pressures are different), and when there are problems as a result of the commercial brass and primers, I won't argue.

Yes, the same problems occur whether or not the rifle is a .30-06, 7.62 x 51mm, or .308.

This is similar to, but not as great as, the difference in the interior volume of a .30-06 M2 Ball, as compared to the 7.62 x 51mm (and between the 7.62 x 51mm and .308, which are slightly different, and definitely not the same). For instance with the same bullet weight, and the same powder charge (in this case USGI) loaded in the M2 Ball .30-06 (7.62 x 63mm) as compared to the 7.62 x 51mm, the 7.62 x 51mm will have approximately 100 lbsft less of muzzle energy, and approximately 100 ft/sec less velocity. Further, the yaw of the bullet at about 800 to 850 yards, is too great to consider it as being stable (it is inaccurate beyond that distance). Meanwhile the .30-06 M2 Ball yaws too much to be considered as stable beyond about 1,175 to 1,200 yards. Yes, I know that some shooters use M1A's to shoot at 1,000 yards with their 7.62 x 51mm or .308 versions. In order to do so they are loading to chamber pressures exceeding 60,000 psi, which is not a safe thing to do over the long term.

`

[BattleRifleG3]

I did have the impression that one should use military 7.62x51mm ammo in an M1 Garand as opposed to commercial 308. Here's a question though - what about 270 Winchester?

[Ben Hartley]

Best I know is that 7.62 NATO and .308 Winchester are not the same. Close, maybe, but not quite. I'll see if I can dig up the exact differences for you -- it may take awhile, though.
Fulton Armory (www.fulton-armory.com) will build you what they call a "Service Grade" M1 in .30-'06, .308, or .270. It'll cost you $1400 -- ok, ok, $1395.95.
HTH
Ben

Didn't take as long as I thought it would! The following -- long, sorry -- is from the CSP M1/M14 forum discussion. Please note that this is all in reference to .308/7.62. When you start talkin' 'bout Jack O'Connor's pet, why, you're on your own! HTH
Ben
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7.62 NATO vs. 308 WIN
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Posted By: Jocko <Send E-Mail> Date: Tuesday, 16 May 2006, at 3:58 am
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Is there a big difference in the two rounds?
If one has an M1A chambered in 7.62 Nato can .308 Win be fired in it? How bout the same question in reverse?
Are there any dangers in the swopping of these two cartridges?
If someone bought an M1A and it is not clearly marked for a certain cartridge, couldn't this be dangerous?
Input wanted >>>> thanks
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Posted By: ltcboy <Send E-Mail> Date: Tuesday, 16 May 2006, at 6:02 am
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Please open link [goes to downloadable xxxxxxxx.pdf file; you'll need Adobe Reader to do so]
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http://www.surplusrifle.com/shooting...nato/index.asp
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Posted By: Gus Fisher Date: Tuesday, 16 May 2006, at 10:46 am
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If you have a "tight" .308 chamber as seen in NM rifles, I would not shoot foreign surplus 7.62mm in it.
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I ran across one such Springfield Armory built M1A while teaching an M14 Police Armorer's course. It would NOT chamber a 7.62mm GO headspace gage, but would accept a .308 win. GO gage. It had a G.I. barrel in it and was only marked 7.62mm.
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If you have a "loose" 7.62mm chamber, then shooting .308 ammo could cause your ammo to stretch severely and thereby shorten case life and or stretch to the point the case would crack.
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What I suggest to people is you want the best in accuracy, get it chambered rather tight in .308. If you want to shoot both and ESPECIALLY FOREIGN SURPLUS, get it chambered so it accepts the 7.62mm GO gage, but does not accept the .308 Field Reject Gage. HTH

[Gyrene]

BattleRifleG3 - I have seen a few M1 Garands set up as .270's. W H Y ???

I think that is an effort to solve a problem that doesn't exist!

They shoot ok, but no better than a .30-06 M1 Garand.

The U. S. Navy M1 Garands in 7.62 x 51mm were essentially very accurized rifles, and performed admirably, however no better than an equally prepared M1 Garand in .30-06. The U. S. Navy was trying to get away with only making an investment in rifle barrels, yet staying within the agreement that they would use NATO 7.62 x 51mm ammo.

I heard of one that was rebuilt in 7.92 x 57mm Mauser (8mm Mauser)W H Y ???, and performance was ok, and close, but not as good as the M1 Garands in .30-06, .270, and/or 7.62 x 51mm.

You have probably guessed correctly, that I prefer the M1 Garands to be in their original caliber, because that is what they were designed for, and that is why they usually work best in .30-06 configuration. I know that the original M1 Garands (WAAAAY BACK), were built as .276 Cal., and I would love to have one (BUT THAT ISN"T ABOUT TO HAPPEN)! General Douglas MacArthur saw the winds of war on the horizon, and made the decision that M1 Garands were to be manufactured to fire .30-06 ammo. The U. S. Military Logistics system proved to be very robust in WWII, but it might not have been able to handle another caliber, and especially with the .276 being a major use item.

`

[troy2000]

I love it when some of you guys get all scholarly on us; I learn stuff. Sometimes it's stuff good to know, that it would never have occurred to me to ask or wonder about.

[BattleRifleG3]

To me, an M1 Garand in 8x57mm Mauser is heresy. I agree that the usefulness of non-30-06 rounds in the M1 Garand is limited. Just that the 270 is derived from the 30-06 and the 308 is its similarly powered successor. I'm just wondering if a person could easily pick up any 270 ammo and use it in a 270 Garand and worry less about the pressure differences between loads than between sporting and military 30-06 ammo.

[myarmor]

Originally Posted by BattleRifleG3

.... I'm just wondering if a person could easily pick up any 270 ammo and use it in a 270 Garand and worry less about the pressure differences between loads than between sporting and military 30-06 ammo.

Simple answer...just load your own. Then you have complete control and peace of mind.
Also too you need to take into consideration that the 270 has a higher working pressure than either the -06 or 308. Not much but a little more:
http://www.leverguns.com/articles/saami_pressures.htm

[BattleRifleG3]

My question though was regarding use of any common ammo out there. Ie are all the standard hunting loads close enough that the gas system could be tuned to take them all (with a few exceptions) without damage?

[Gyrene]

BattleRifleG3 - If the M1 Garand had a tuneable pressure capability, like the FN-49 and some other rifles, it could be made to work very well with the various types of ammunition, powders, . . . There are some aftermarket gas cylinder plugs that can be tuned to a specific load, but if you change anything in the load, you have to retune it.

I am positive that what you are looking for, is an elusive goal, that many have tried to discover before, and all have failed.

The M1 Garand as designed, is an excellent semi-auto rifle, which contributed heavily to winning WWII, and no attempt to change it or redesign it, or . . . has ever made a worthwhile improvement. Some might say that the M-14 was a design improvement, however it only has a few more desireable characteristics (such as the removeable magazine), which were included in some of the original M1 Garand Designs, but rejected by the bean counters.

I can't figure out why anyone would want to change it from a .30-06! Of course as far as I'm concerned there are only 3 rifle calibers that are really needed: .22 Cal Rimfire; .30-06; and .45-70; everything else is just an attempt to solve a problem that doesn't exist.

The problem in trying commercial ammo, number one, we don't know if the powder used will have the correct burn rate, or pressure, or its range of pressures will be within the correct parameters for the M1 Garand timing, and pressures. Commercial loaders can and do use various powders for the same load, they do change the lot number if they change powder, by type, though I am not sure they change the lot number if the powder is the same type, but from a different lot number (they should).

I have found commercial ammo loaded with stick powder and in the same box and same lot some of it was loaded with flake powder. In a bolt action gun the change is not more than a slight problem with accuracy, but the burn rate, and pressure peak are a very big concern when the cartridges are used in an M1 Garand. The military cartridges are thicker which changes the internal volume, changing the internal ballistics. The military primers are also made of a thicker material, reducing the chance of firing out of battery; which is not something you want to have happen! I believe the military cases are a tougher brass, too, cutting down on failure to extract problems.

Most of the Commercial loaders just do not load properly for the M1 Garand. There are some that load specifically for the M1 Garand, but they are not readily available. All of them are capable of loading correctly for the M1 Garand, when they have a Government contract!

`

[Indy]

I am not sure your original question was answered. If it was I apologize for my reply. A 308 Garand is essentially a M1A without the magazine and other slight changes. Also, the 7.62 x 51mm is not a 308win. 7.62mm/308 Garands will operate best around 50,000psi of pressure. Care must be taken when reloading to use powders that function around that pressure range and the burn rate is close to 4895. Actually low pressure will cause extraction and ejection problems. I have fired commercial ammunition in my Garand,but it is not recommended. Please keep in mind projectile weight is important to, keep bullet weights in the 147 to 170 range. I have heard of shooting 180 gr bullets, but operation seemed to change. I have loaded and shot tracers without any issues. I prefer Winchester large rifle primers, they seem to be harder and reduce the chance of slamfires.
One last thing clean your Garand upside down to keep solvent and crud out of the gas system.
Indy

[Gyrene]

Indy - The pressure of 50,000psi is in the upper range for an M1 Garand, but the M1 Garand can handle it, as it was designed to handle about 47,000psi for the M2 Ball ammo, and were proof tested to 75,000psi.

Keep in mind, the 7.62 x 51mm M-14 was designed to have approximately 54,000 to 56,000psi in its normal operation with USGI ammo. The .308 is higher at 62,000psi for normal factory loads.

The M2 Ball .30-06 in an M1 Garand (in good condition) can fire out to 1,175 yards with reasonable accuracy and the bullet will begin yawing and go unstable beyond that, at around 1,200 yards. Who in the world shoots (or even has a range to shoot that distance) that far out? Competition shooters shoot out to 1,000 yards fairly regularly.

The M1A in .308 (in good condition) can fire out to about 800 yards before the bullet begins yawing and it goes unstable beyond that, by 900 yards. I know that some shooters do very well in 1,000 yard competition with their M-14/M1A's, but they are loading to 65,000psi or more to get there. The M-14 has a forged receiver (the strongest a receiver can be made), and an M1A is an Investment Cast receiver (not bad, but not the strongest), and these guys are pushing it.

The M1A/M-14 system has enough differences in the Gas Cylinder and Operating Rod, that higher pressures can be used more safely.

Sierra Match King HPBT bullets at 168 grains, with IMR 4895 powder (loaded to your Hand Loading Manual guidlines) will provide the best accuracy for either the M1 Garand, or the M1A/M-14.

`

[Indy]

Thanks for the additional information.
Indy

[Aligater]

I read a post on the CSP Garand/M1A forum saying that people have had "good results" using Remington Core Lock 150 and 165 grain ammo in the Garand. I don't know about the 180.
Aligater

[eclancy]

Gentemen,
On my site I have posted Ordnance files dealing with problems with M1 Ball ammo. This was one of the main reasons that Ordnance went to the M2 Ball ammo. If you read into these files you will find alot of data on the ammo question. Take the time it might help you guys.
Thanks again
Clancy