I hope I'm posting this in the right place...After getting my garand, and making my first range trip, I realized the surplus ammo is not "range friendly" in my local rifle tube. I bough & shot some Remington 165Gr .30-06 Springfield Rounds. All seemed to go well, then I started to see multiple postings online regarding use of newer commercial ammo in the garand, and the need for an adjustable gas plug.
I decided its better to be safe, than sorry, and ordered one of these: http://www.intlmidway.com/intl/eproductpage.exe/ShowProduct?saleitemid=777146.
My question is, am I overreacting? Has anyone experienced many problems with m1's and normal commercial ammo? I'm not interested in putting anything heavy through it, 150 - 165 gr is just fine for me, until I can get outside, and use up some of that M2 Ball I have. I figured it would be worth $35 to have the peace of mind, and the option to make changes, if necessary. This will work in the time being, until I can get on board with reloading (my ultimate long term goal).
Thanks!
The M1 was developed using 173g bullets over IMR 4895 powder.
The problem is not the bullet weight or the pressure at the chamber. The problem is pressure at the gas port. IMR 4895 is a relatively fast burning powder. Most modern commercial ammo is loaded with slower burning powders to help reduce the perceived recoil. These powders will have too high of pressure still in the barrel when the bullet passes the gas port and WILL raise the the gas cylinder pressure. The result is a bent op rod. I have read post of shooters trashing their op rod with just one box of commercial ammo.
So yes, the adjustable gas plug is required for commercial ammo.
HTH
Douglas
I'm far from an expert on it but I would say that if you're going to shoot commercial ammo in your M1, or M1A you should use one of the adjustable gas plugs. I have a Schuster in mine and it hasn't had any issues so far. The other one I've seen for sale is the McCann (not sure it that was spelled right) unit. The Schuster has an adjustable plug/allen screw set up in the plug. The McCann has different vented screws you install in the plug based on what you are shooting through it. I can't say which is better, I bought the Schuster as it was on sale at Brownell's.
What is probably more damaging to the M1 and M1A than the bullet weight (Military armor piercing bullets weighed about 163 grains and military match bullets weighed about 172 grains- so a 165 grn. hunting type bullet should be okay) is the burning rate of the powder. If the burning rate is too slow (heavier bullets "like" slow burning powders) the pressure when the bullet passes the gas port is still high enough to cause damage in the gase system or to damage the operating rod.
I don't know what powder the commecial manufacturers use for their 150 and 165 grn. hunting loads. I do know that the bolt action, pump and even semi-auto deer rifles seem to eat it all with no issues. The M1 and M1A were designed for a certain port pressure and the military ammo was loaded with a powder(s) that gave them the required bullet velocity and the required pressure at the gas port.
If you start reloading for you M1 (gotta do something with that new brass, right) having the adjustable plug will allow you to experiment with powders and bullet weights other than the powders in the recommended burning rate.
Using powders that are too slow will cause damage. I ran across my old M1A operating rod I cracked (twice) many years ago from using powder that had too slow a burning rate.
I don't think your M1 won't be acceptable for NRA or CMP match shooting with that adjustable plug in it but it'll still shoot just fine and you can adjust it so that the gas system gets enough gas to operate but not enough to hurt the rifle.
Thanks for the fast, and informative responses! I ordered the schuster plug last night, and will put it in this weekend. After all, ANY excuse to shoot again is well worth it.
I'll back up what's already been posted on Port Pressure and powder burn rate.
Pay CLOSE attention to this, or you will eventually break something.