Strongest 308 Win brass for the M305, M14?
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Let's try to explain this in a manner that makes sense.
The difference between 7.62 and 308 ammo is the 7.62 brass usually heavier. The important feature is a thicker (higher) web in the base. Because some military rifles don't support the entire head, this is the important feature. I have seen some "tuned" M14's with polished ramps that left the head less supported.
7.62 and 308 ammo are loaded to very similar pressures, so pressure in not an issue.
7.62 ammo is loaded with medium fast powder so that the gas port pressure is not too high. When buying 308, you are safe with 150 gr bullets, becasue these will be laoded with faster powder. A heavy bullet would have slower powder and beat up the rifle.
Headspace. There is a lot more to proper chambering than headspace. My target rifles are made with what we call "0" headspace. No clearance between a chamber shoulder and the cartridge shoulder. Let's say the chamber was cut 20 thou too deep, but the bolt face has the correct position in relation to the chamber. 20 thou is considered to be way too much headspace, but if it is just a too deep chamber, it is not dangerous, although ignition might not be very reliable. On firing, the case will set back onto the bolt face, maybe stretch badly and the shoulder will blow forward. The worst possible "headspace" occurs when you shoot a 308 round in a 30-06 rifle. happens all the time. The half inch of exceess headspace just yields a straight-wall case that has no neck.
And this is what we have in the typical military 7.62. The chamber is 10 to 15 thou deeper than what we would prefer. The military want a dirty/dented case to chamber and fire. They don't care if the resulting empty case is stretched.
If you are a reloader, there is a "fix". The first time you load the case, use 2 grains less than what you would usully use and seat the bullet long enough to engage the rifling real hard. This will minimise case stretch. On subsequent sizings, full lenght size, but only enough to permit the case to chamber. If you don't push the shoulder back the last 4 thou, you have 4 thou less headspace.
When a gunsmith "checks the headspace" he is really concerend about the clearance from the bolt face to end of the barrel. Too much clearance could mean that too much case head is not supported. This has nothing to do with headspace, but is the problem that is dangerous.
Both 308 and 7.62 will work well in the M14. If you use military brass the load should be reduced about 2 grains to compensate for the smaller case capacity. Pressure and velocity will be about the same.
I prefer 7.62 brass because once fired is so cheap to buy and I don't get so upset when i lose a few cases.
The difference between 7.62 and 308 ammo is the 7.62 brass usually heavier. The important feature is a thicker (higher) web in the base. Because some military rifles don't support the entire head, this is the important feature. I have seen some "tuned" M14's with polished ramps that left the head less supported.
7.62 and 308 ammo are loaded to very similar pressures, so pressure in not an issue.
7.62 ammo is loaded with medium fast powder so that the gas port pressure is not too high. When buying 308, you are safe with 150 gr bullets, becasue these will be laoded with faster powder. A heavy bullet would have slower powder and beat up the rifle.
Headspace. There is a lot more to proper chambering than headspace. My target rifles are made with what we call "0" headspace. No clearance between a chamber shoulder and the cartridge shoulder. Let's say the chamber was cut 20 thou too deep, but the bolt face has the correct position in relation to the chamber. 20 thou is considered to be way too much headspace, but if it is just a too deep chamber, it is not dangerous, although ignition might not be very reliable. On firing, the case will set back onto the bolt face, maybe stretch badly and the shoulder will blow forward. The worst possible "headspace" occurs when you shoot a 308 round in a 30-06 rifle. happens all the time. The half inch of exceess headspace just yields a straight-wall case that has no neck.
And this is what we have in the typical military 7.62. The chamber is 10 to 15 thou deeper than what we would prefer. The military want a dirty/dented case to chamber and fire. They don't care if the resulting empty case is stretched.
If you are a reloader, there is a "fix". The first time you load the case, use 2 grains less than what you would usully use and seat the bullet long enough to engage the rifling real hard. This will minimise case stretch. On subsequent sizings, full lenght size, but only enough to permit the case to chamber. If you don't push the shoulder back the last 4 thou, you have 4 thou less headspace.
When a gunsmith "checks the headspace" he is really concerend about the clearance from the bolt face to end of the barrel. Too much clearance could mean that too much case head is not supported. This has nothing to do with headspace, but is the problem that is dangerous.
Both 308 and 7.62 will work well in the M14. If you use military brass the load should be reduced about 2 grains to compensate for the smaller case capacity. Pressure and velocity will be about the same.
I prefer 7.62 brass because once fired is so cheap to buy and I don't get so upset when i lose a few cases.
Starscream
CGN frequent flyer
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There's nothing bad with federal persay, it meets spec but federal brass is a tad softer (I had to trim all the federal brass, and none of the winchester brass), so it's safe to assume that the federal brass is going to give out sooner then winchester or remington brass.
Ganderite, that was a good read, thanx for spellin that out.
In another thread, guys were talking bout leaving a krieger barrel "short chambered" , running it with a norc bolt....... and using that short chamber to make up for the extra headspace found in most norcs..... I was thinkin this would cause a situation where the case head is no longer properly supported and would result in a dangerous situation...... your thoughts???
In another thread, guys were talking bout leaving a krieger barrel "short chambered" , running it with a norc bolt....... and using that short chamber to make up for the extra headspace found in most norcs..... I was thinkin this would cause a situation where the case head is no longer properly supported and would result in a dangerous situation...... your thoughts???
My understanding of "short chambered" is different.
A new barrel is supplied that is threaded and ready to screw in. The installing gunsmith can fit it so the barrel to bolt face clearance is perfect. It is partially chambered (short chambered). The last quarter inch or so of the chamber has not been cut. He then finishes cutting the chamber, being careful to cut no more than just enough to chamber a round.
A new barrel is supplied that is threaded and ready to screw in. The installing gunsmith can fit it so the barrel to bolt face clearance is perfect. It is partially chambered (short chambered). The last quarter inch or so of the chamber has not been cut. He then finishes cutting the chamber, being careful to cut no more than just enough to chamber a round.
