The Firing Line Forums - View Single Post - newbie- Loading .308, and soon .223- recommendations

Bart B. · October 3, 2012, 06:13 AM

OSOK, you're comparing velocity across different barrels. Of course that's going to happen with different amounts of throat erosion plus bore and groove dimensions as well as firing pin impact on primers. Even with the same rifle and ammo used by 3 or 4 different people holding the rifle, there can easily be 70 fps difference in velocity. Changing powder and primer lots for a given load will also cause that much spread in velocity in the same barrel. The 53 fps spread your observed across three barrels is normal for service rifles. It happens with match and sporting rifles, too, I've seen it with mine shooting the same load in a dozen or so barrels for the same cartridge, but accuracy was the same.

I was referring to accuracy; that's independent of average muzzle velocity.

October 3, 2012, 06:13 AM	#21
Bart B. Senior Member Join Date: February 15, 2009 Posts: 8,927	OSOK, you're comparing velocity across different barrels. Of course that's going to happen with different amounts of throat erosion plus bore and groove dimensions as well as firing pin impact on primers. Even with the same rifle and ammo used by 3 or 4 different people holding the rifle, there can easily be 70 fps difference in velocity. Changing powder and primer lots for a given load will also cause that much spread in velocity in the same barrel. The 53 fps spread your observed across three barrels is normal for service rifles. It happens with match and sporting rifles, too, I've seen it with mine shooting the same load in a dozen or so barrels for the same cartridge, but accuracy was the same. I was referring to accuracy; that's independent of average muzzle velocity. Last edited by Bart B.; October 3, 2012 at 06:46 AM.