M1 garand, 150gr, 165gr, 180gr?

[hmudd13]

http://www.ar15armory.com/forums/style_images/ar15armory/spacer.gifI purchased an adjustable gas plug and was wondering if it needs to be adjusted for the different bullet weights?
I know it does for commercial/milsurp, but does weight factor in here?
Couldn't find any info on this subject using the search.
Thanks in advance.

[Zombie Steve]

The gas plug is going to help with port pressure. Start reading page 10 here (http://www.zediker.com/downloads/14_loading.pdf)- it's the same concept for the M14 and the M1 Garand. Bullet weight will affect port pressure in that the heavier bullets usually use slower burning powders that are "late bloomers", which increases port pressure, so the answer to your question is it very well could need adjustment depending on the load.

All that said, I'd stick to bullets in the 150 - 168 grain range. IIRC, Garands have a 1:10 twist rate, so it should stabilize 180's, but again, it was designed for 150's. It's just not something I'd push the envelope with...

Good luck. Let us know how it turns out.

[jmg8550]

I agree with the above post. I won't shoot any bullet over 168gr. And I'm not really sold on the Schuster adjustable gas plug. Seems like a pain to use because when you do clean the gas system, you have to disassemble the the plug. Then you have to start all over adjusting it.

[hmudd13]

thanks guys, I only have 20 rds of 180, I'll use them up first, then adjust to the lower grains for good.

[jmg8550]

Be careful with the 180's. If they are modern commercial loads, they may end up bending your operating rod. Or they could permanently damage your rifle.

Modern commercial loads are designed more for modern rifles. The M1 was never meant for them. The powders used today are quite a bit different. If you want to use commercial ammo, Federal has cartridges for the M1.

[Zombie Steve]

That's where the adjustable gas plug comes in... designed to vent some gas so it doesn't batter your op rod.

[kidicarus13]

Be careful with the 180's. If they are modern commercial loads, they may end up bending your operating rod. Or they could permanently damage your rifle.

Modern commercial loads are designed more for modern rifles. The M1 was never meant for them. The powders used today are quite a bit different. If you want to use commercial ammo, Federal has cartridges for the M1.

How will you know if the operating rod is bent? Isn't it internal?

[jmg8550]

The rifle may not cycle correctly. Or if it bends enough, it can break your stock.

Like I said before, the adjustable gas plug does work, it just is a pain to adjust every time you clean the gas system. I just choose not to run anything heavier than 168's. Which should be the heaviest you would need for hunting or High Power competition.

[hmudd13]

Seems like a pain to use because when you do clean the gas system, you have to disassemble the the plug. Then you have to start all over adjusting it.
Why would the plug need dis-assembly? Wouldn't a good soak and a blow dry work?

[10x]

National Match USGI rounds use a 173 grain bullet. That is usually considered maximum bullet weight for an M1.

20 rounds of the wrong ammo can bend an operating rod to the point the rifle won't cycle correctly and the rod will need to be replaced.

If it were me I would not shoot 180 grain commercial ammo in the M1.

[hmudd13]

I actually got to shoot with the new valve this weekend and it worked like a charm.
Got rid of the few 180/165grains that I had and now I'll use 150 only.
The only drawback is it won't cycle the M1 specific ammo without re-adjustment.
I'll hang on to the original valve should I ever find myself using some Milsurp again.
Thanks for the input all.