Using 4350 in a M1A


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IM391
October 11, 2011, 02:17 AM
What does anyone suggest for using IMR 4350 in reloading .308 for a M1A. I've heared two views of the arguemnt.
One says its too slow and will damage the operating rod, the other says it's ok as long as one stays under the prescribed M1 or M1A velocities recommended for the bullet.
How does one know if the operating rod is bending or broken? Is that all that will happen?

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ArchAngelCD
October 11, 2011, 03:07 AM
The velocities mean nothing, it's the pressure curve that matters. I would not use 4350 in any 30-06 or .308 semi-auto because the pressure is still building when it hits the gas port. I suggest using H4895, IMR4895, AA2495 or AA2520 for your ammo.

You will know the op-rod is bent when the rifle no longer fires. By then you will need a new one and that will cost you a lot.

P-32
October 11, 2011, 03:59 AM
IMR 4350 will bend your op rod! It's too slow of powder for the gas system, no matter what the load is. Works well in a bolt gun. (really well in a bolt gun) IMR 4895 hru IMR 4064 are good powders along with any other powders with the same burn rates are what is needed in this case. Some of todays reloading manuals also have load data for gas guns in the match bullet sections.

You will know the op-rod is bent when the rifle no longer fires. By then you will need a new one and that will cost you a lot.

A true statement. Today, hens teeth are easier to find and cost less than a op-rod for a M-14/M-1A. I would also bet somebody has never reloaded for a M-1 Garand or M-1A.

Another thing to think about is the primer. The use of Federal primers is not recommended in the match shooters circles. The M-1A along with the M-1, M-14, M-16 and all clones have free floating firing pins. Federal primers are easier to set off than about any other primer. This means a round could be set off before the bolt is fully in battery. You can not have high primers either. I use CCI primers with good results. CCI also makes a mil spec primer which reduces the chance of slam fires even more. If you pull a round which has been chambered by full bolt speed and look at the primer you will see what is called a "dimple" in the primer from the free floating firing pin. Not a big deal. These rifles have done this from the time of invention, but you still have to careful.

BruceB
October 11, 2011, 08:40 AM
The M1a gas system is DIFFERENT from that of the Garand.

It uses a "gas-cutoff" method of operation, where ther gas flows into the side of the piston and expands in all directions. As soon as the piston moves a very short distance, the gas flow is , literally, "cut off".

This means that the TIME of the pressure pulse is quite short, unlike the Garand sytem in which the piston is pushed by the gases for its entire cycle.

The risk of damage in the M1A with slow powders is much less than it is in the Garand.

Even so, 4350 is not a good choice, and I wouldn't use it with conventional jacketed-bullet loads. It's just too slow for efficiency, and there are many powders which are far better-suited to the M1A rifle.

4350 isn't a good .308 powder even in a bolt-action rifle, and it certainly isn't a good idea to use it in autoloaders.

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