Opinions wanted

ronl · May 3, 2009, 11:20 PM

I load .308 for an M1A and a Rem. 700. The chamber of the M1A is slightly longer than that of the 700. The difference is such that rounds that will chamber in the M1A will not chamber in the 700. I have started segregating brass for each rifle, as I am leaving the M1A rounds longer, so the brass will not be stretched as much when firing. Perhaps this will get an extra firing or 2 out of the brass. When sizing for the M1A I set the die for just touching the ram and do not run it in the extra 1/4 turn. I then trim and load the bullets. Anyone else run into the same thing? I know the Mil-spec chamber can be longer than the civvie chamber, as my two rifles demonstrate. I could bump the shoulders back to civvie standard, but the bullets would simply stretch again. All ammo has fired fine. Do all you old-time reloaders agree with my thought process here?

30Cal · May 4, 2009, 11:19 AM

I would buy a comparitor or case gage and set the die to do the minimum sizing required for both rifles to cycle (take 700 fired brass and set the shoulder back by 0.002-0.004").

James R. Burke · May 5, 2009, 04:01 PM

I am sure this wont help you out. But awhile back I was working up a load for my cousins .270 win Model 700. I found the C.O.L. to be really long. They looked so long I triple checked them, then made up some dummie rounds just to make sure that they functioned o.k. when cycled thru the bolt. Must have had just a really long chamber. The first thing we noticed was how the groups got alot tighter. He said that gun was never very accurate until we worked up that load. We where getting 5-shot groups in 3/4" or better at 100 yards with a really cheap scope.

dmazur · May 5, 2009, 09:32 PM

I load .30-06 for a Garand and a MRC 1999 bolt-action. Not exactly the same thing you're doing, but close.

My understanding (which I will acknowledge is limited) is that brass should be sized to SAAMI minimum for "gas guns", using a full-length resizing die. Some argue that a small base die is a requirement, and others say not to worry as long as you're not trying to reload once-fired brass from machine guns (which apparently have such a generous chamber that the base of the brass can expand...and only a small base die will restore this.)

And, instead of using approximate die setups, gas-gun reloaders recommend using a Wilson type cartridge headspace gauge to set up your press. Adjust your die until the brass is flush with the lower step, which is SAAMI minimum.

To go along with this recommendation is use of chamber headspace gauges to make sure your rifle doesn't have excessive headspace. For .30-06, I believe the difference between GO and NOGO is only 0.006", so if your rifle doesn't have excessive headspace, the worst the brass is stretching is 0.006".

Other ideas for prolonging brass life include lightly lubing the brass for use in gas-gun competition shooting. (This isn't the same as field conditions, where lube can pick up dirt...) As gas-guns start extracting the brass while the brass is still gripping the chamber, a light lube helps reduce stretch near the head of the brass.

I believe that resizing to maximize brass life is entirely acceptable for the 700, which can't slamfire on a failure of the bolt to close. (You do this manually, of course, and have tremendous mechanical advantage at your disposal with the bolt action.) However, it is a questionable practice for a gas-gun, which has to close the bolt completely each time, every time, to be safe.

Nnobby45 · May 5, 2009, 09:51 PM

Military semi-autos are made with more chamber tollerance for reliable feeding.

In some M1 Garands, the headspace can be as much as .010, with .007 considered the limit or even too much for a bolt actiion hunting rifle.

Quote:

Some argue that a small base die is a requirement, and others say not to worry as long as you're not trying to reload once-fired brass from machine guns (which apparently have such a generous chamber that the base of the brass can expand...and only a small base die will restore this.)

Do not reload ammo fired in a machine gun. It isn't a matter of needing small base dies. It's a matter of the brass being fired in a chamber with so much headspace that the case has stretched too far to be safely reloaded, even if a small base die can restore it to proper dimensions.

There's no need to argue if small base dies are a requirement. If standard dies do not size the case enough to chamber in some semi-autos, then you need small base dies. Other wise, you don't. As stated, military rifles tend to have bigger chambers than semi-auto sporting rifles.

SL1 · May 6, 2009, 11:12 AM

The .308 Winchester and the 7.62x51 Nato actually have different dimensions for case LENGTH and different "Go" and "No Go" headspace gauges. So, the difference is not just a matter of the military chambers typically being at the long end of the allowable size range for civilian chambers.

Sizing to the proper dimensions for each chamber seems like a good idea to extend case life. It should be easy to keep brass loads segregated if you use different headstamps for the different loads. As long as your brass chambers easily in YOUR gun, then it is sized enough for YOUR gun.

SL1

May 3, 2009, 11:20 PM	#1
ronl Senior Member Join Date: December 2, 2007 Posts: 1,100	Opinions wanted I load .308 for an M1A and a Rem. 700. The chamber of the M1A is slightly longer than that of the 700. The difference is such that rounds that will chamber in the M1A will not chamber in the 700. I have started segregating brass for each rifle, as I am leaving the M1A rounds longer, so the brass will not be stretched as much when firing. Perhaps this will get an extra firing or 2 out of the brass. When sizing for the M1A I set the die for just touching the ram and do not run it in the extra 1/4 turn. I then trim and load the bullets. Anyone else run into the same thing? I know the Mil-spec chamber can be longer than the civvie chamber, as my two rifles demonstrate. I could bump the shoulders back to civvie standard, but the bullets would simply stretch again. All ammo has fired fine. Do all you old-time reloaders agree with my thought process here?

May 5, 2009, 09:32 PM	#4
dmazur Senior Member Join Date: July 5, 2007 Location: Pacific NW Posts: 1,310	I load .30-06 for a Garand and a MRC 1999 bolt-action. Not exactly the same thing you're doing, but close. My understanding (which I will acknowledge is limited) is that brass should be sized to SAAMI minimum for "gas guns", using a full-length resizing die. Some argue that a small base die is a requirement, and others say not to worry as long as you're not trying to reload once-fired brass from machine guns (which apparently have such a generous chamber that the base of the brass can expand...and only a small base die will restore this.) And, instead of using approximate die setups, gas-gun reloaders recommend using a Wilson type cartridge headspace gauge to set up your press. Adjust your die until the brass is flush with the lower step, which is SAAMI minimum. To go along with this recommendation is use of chamber headspace gauges to make sure your rifle doesn't have excessive headspace. For .30-06, I believe the difference between GO and NOGO is only 0.006", so if your rifle doesn't have excessive headspace, the worst the brass is stretching is 0.006". Other ideas for prolonging brass life include lightly lubing the brass for use in gas-gun competition shooting. (This isn't the same as field conditions, where lube can pick up dirt...) As gas-guns start extracting the brass while the brass is still gripping the chamber, a light lube helps reduce stretch near the head of the brass. I believe that resizing to maximize brass life is entirely acceptable for the 700, which can't slamfire on a failure of the bolt to close. (You do this manually, of course, and have tremendous mechanical advantage at your disposal with the bolt action.) However, it is a questionable practice for a gas-gun, which has to close the bolt completely each time, every time, to be safe. __________________ .30-06 Springfield: 100 yrs + and still going strong

May 4, 2009, 11:19 AM	#2
30Cal Senior Member Join Date: December 3, 2002 Posts: 1,264	I would buy a comparitor or case gage and set the die to do the minimum sizing required for both rifles to cycle (take 700 fired brass and set the shoulder back by 0.002-0.004").

May 5, 2009, 04:01 PM	#3
James R. Burke Senior Member Join Date: January 3, 2009 Location: U.P. of Mich/Quinnesec Posts: 1,897	I am sure this wont help you out. But awhile back I was working up a load for my cousins .270 win Model 700. I found the C.O.L. to be really long. They looked so long I triple checked them, then made up some dummie rounds just to make sure that they functioned o.k. when cycled thru the bolt. Must have had just a really long chamber. The first thing we noticed was how the groups got alot tighter. He said that gun was never very accurate until we worked up that load. We where getting 5-shot groups in 3/4" or better at 100 yards with a really cheap scope.

May 6, 2009, 11:12 AM	#6
SL1 Senior Member Join Date: November 8, 2007 Posts: 2,001	The .308 Winchester and the 7.62x51 Nato actually have different dimensions for case LENGTH and different "Go" and "No Go" headspace gauges. So, the difference is not just a matter of the military chambers typically being at the long end of the allowable size range for civilian chambers. Sizing to the proper dimensions for each chamber seems like a good idea to extend case life. It should be easy to keep brass loads segregated if you use different headstamps for the different loads. As long as your brass chambers easily in YOUR gun, then it is sized enough for YOUR gun. SL1