Powder charge bolt vs gas

[mcxring]

Most of the reloading books that I have will talk about a gun in that caliber followed by the loading chart, most of the guns are bolt action, my guns are (AR-15 AR-10) gas guns, should I been dropping the powder charge for my gas guns say by 2 grains or so than what is recommended for a bolt action gun.
Thnx Mike

 

[Cort]

Mike,

If you go to the .223 link here on the forum, there are separate links from Sierra specifically giving loading charts for the AR-15 and for .223 bolt guns. The .308 Win link does not have the separate links listed. I believe the issue with gas guns has to do with the amount of gas pressure developed by the load and the timing of the gas impulse. I am not sure why the .308 Win doesn't have a separate load map for AR-10's but one is not listed.

Cort

 

[bigedp51]

With the AR direct impingement gas system you don't have worry about bending a op rod. What you do have to worry about is being over gassed and the bolt starting to open while the case is still making contact with the chamber walls and has not sprung back to its normal size.

This will cause brass smearing from the ejector button and the bolt face below the extractor, this will depend on chamber size/type, throating, buffer weight and the buffer spring weight..

As with any reload start low and work up and visually check your cases and on a AR this means a brass catcher or a helper with asbestos gloves.

 

[dboyles]

I find it interesting that Sierra's load data has a higher published max for H322 in AR-15s than in bolt guns. The same thing is true with Varget in lighter bullet weights (52-55gr). I actually emailed Sierra about it several months ago and received a fairly standard response that the load data is representative only of the actual firearm used in the tests.

 

[CJ6]

Hornady has a SERVICE RIFLE section for 223, 308, 30-06 (M1 Garand). Generally the loads are lighter.