Maximum safe pressure for the M1 Garand


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GarandOwner
September 24, 2007, 11:51 PM
Sorry if this seems like a dumb question, but I am still fairly new to reloading: Does anyone know what the maximum safe pressure is for the M1 Garand for reloads? Or is it more about the speed? I know that IMR 4895 is a good powder for it, but I am thinking of branching out and trying something different. (Specifically using 168 grain A-max bullets with a starting load of 55 gr. of H4350) Lee's reloading data shows this starting PSI of 48455 PSI . Would this be safe to try, or is H4350 too slow of a powder to use? Thanks any and all information would be helpful

Oh and I tried doing a thread search so this wouldnt be the 1001st thread on reloading for the garand, but I couldnt find the answer to my question

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ReloaderFred
September 25, 2007, 12:02 AM
You'll want to stick with powders in burning rate between IMR 3031 as the fastest and IMR 4320 as the slowest. If you use a slow powder like H4350, you run the risk of too much port pressure, which will bend that expensive operating rod.

The Garand is designed for ammunition with an average chamber pressure of 50,000 psi.

Hope this helps.

Fred

GarandOwner
September 25, 2007, 12:13 AM
Thanks Fred that makes sense now. Im guessing then that Port pressure is independant of chamber pressure? (Meaning just because one round has a chamber pressure of 50,000 and a safe port pressure doesnt mean that another round with a chamber pressure of 50,000 will have also have a safe port pressure.) My next question would be, how can you tell what is a safe maximum load for one of the powders within this range? Or should they be about the same as the max load for any gun using these powders?

ReloaderFred
September 25, 2007, 01:42 AM
Just load for the Garand like you would any other 30-06, but stay in the powder burn rate range I gave you. One thing though, I've owned as many as 9 Garands at one time, but I'm down to 5 of them right now. Every one I've owned had what might be called a "generous" chamber. They seem to run on the long side for headspace, averaging about .008" over SAAMI minimum. If your rifle is in that range, then you'll get case separations if you size your brass back to minimum. If you have the means, measure your fired brass and then set up your sizing die so you're setting the shoulder back about .002"-.003", and your brass will last longer. I use the RCBS Precision Mic die for both measuring the brass and setting up the die.

Yes, port pressure is independant of chamber pressure. IMR 4895 was made specifically for the Garand and it's an excellent powder for it.

Hope this helps.

Fred

dmazur
September 25, 2007, 01:51 AM
I reload .30-06 for other rifles and I couldn't stand not being able to use Varget in the Garand. It is a little bit on the slow side, which I understand creates too long a pressure pulse at the gas port.

Somewhere I read that it's the energy under the curve that damages the op rod, not the maximum pressure at the port. I know, the pressure's only there for milliseconds, but it makes a difference.

The solution is an adjustable gas nut, if you don't want to be restricted to the safe Garand load data.

To use this, you start with the nut adjusted wide open (no rifle function) and slowly and safely adjust it smaller until you get reliable feed. You would have to go through this procedure each time you change loads, if you ever do.

One way of determining reliable feed, I've read, is to use a single round block in the Garand for this testing. If the bolt comes back far enough to lock the action open with each round, it will definitely be traveling far enough back to chamber a new round. (If you don't do this, sometimes you can get things adjusted so the rifle feeds reliably but you lose last round lock feature...)

BsChoy
September 25, 2007, 06:19 AM
Alot of guys including me use varget in thier garands...it isn't that far at all from IMR4064 which is as ideal as 4895...I've actually heard of varget being called 4064 short cut by some

USSR
September 25, 2007, 07:57 AM
Yes, Varget or even RL-15 would be okay for the Garand. You just can't go as slow as a 4350 burn rate powder.

Don

30Cal
September 25, 2007, 01:05 PM
2650fps is about as fast as you should go with a 168gr. 2550fps is usually pretty good. Pushing for an extra 100fps doesn't really buy you anything---even the wind drift numbers at 600yds won't really change.

rcmodel
September 25, 2007, 01:27 PM
The sixth edition Hornady manual has a chapter on 30-06 loads for the M-1 Garand.

They list safe loads for 7 different powders using 150-155 bullets, 11 powders using 168 grain bullets, and 10 for 178 grain bullets.

Varget is included, as is H-335, RL-12, RL-15, BL-C2, RL-15, WW748, IMR 4895 & 4064, VIHT N-135 & N-150, and others.

http://i81.photobucket.com/albums/j219/rcmodel/KTOG/1224.gif
rcmodel

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