loading for semi auto help

[10XSHOOTER]

42.0 IMR 4064 With a 168. Match load for M-14. Provided by the US Navy for shooting team.
I have loaded 42.0 IMR 4064. with a 175 SMK for 600 yds.
and yes tough primers.

 

[LGKLAS]

Because of the gas system. With slower powders the pressure at the gas port is higher. Autoloaders are designed with a specific port pressure in mind.

The FAL military rifle was designed with an adjustable gas system that allowed for variations in port pressure. The M14 rifle and M60 machine gun were designed with a cutoff-expansion gas system for the same purpose. The cutoff-expansion theory was that higher pressure gas would flow in faster and the first movement of the gas piston would cutoff this higher pressure and the residual gas would expand. And it worked, sort of...ish. But now, by NATO STANAG agreements, port pressures for NATO ammo is controlled by agreement.

The only way to do this is by limiting powder selection to that commonly loaded (in military ammo). For 308 those powders are in the range previously identified.

Thanx riflewoman ; I was curious because I own a RRArms AR-10 (their nomenclature is LAR8) in 6.5CM and it has been cycling everything I've fed it. From factory- Hornadys of various weights. Federal w/130 Berger, Winchester 140 Match, Nosler. My handloads so far for it have been done using H4895 and Superformance. (140 gn bullets). My RRA is direct impingement gas operated. M-60 has piston. Maybe that's a difference. Or a difference in how RRA ported things or their overall design of the gas system ..... Thanx again, in any event. lg

 

[riflewoman]

Direct impingement systems are slightly more forgiving, IMO, than most other gas systems. There is a limit, however, as the 22 Nosler shooters found.

 

[243winxb]

From Sierra- http://www.exteriorballistics.com/reloadbasics/gasgunreload.cfm
Reloading for Semi-Autos and Service Rifles

 

[LGKLAS]

From Sierra- http://www.exteriorballistics.com/reloadbasics/gasgunreload.cfm
Reloading for Semi-Autos and Service Rifles

Great article! Thanx so much for posting it. lg
PS: & I shared it with an army buddy who inherited an M-1 last winter.

 

[KevinThomas]

Glad you guys liked it and found it useful! I included that one as I felt that there were enough differences between loading for autos and other types of actions, that it needed some deeper explanation.