Need More Opinions - The Firearms Forum

nadroj · 01-16-2010, 12:19 AM

I load cal 308 Win for an M1A. Usually use 150 gr, fmj with BLC-2 at 42 gr. Not that particular about brands of brass or projectiles. Everything that I have read says that the min case length is 2.005 and the max overall length is 2.80. I usually trim to min. case length and about 2.76 for COAL. I bought a factory box of Remington standard 308 and a box of Federal 308. The Remington measured avg 2.78 and the Federal measured avg 2.72. Maybe somebody can tell me why the big difference in COAL. Just a curious thought. As you can tell I just shoot for fun. Thank you for your opinions.

bntyhntr6975 · 01-16-2010, 01:31 AM

You didn't mention what projectiles were in the ammo you bought. But, keep in mind that different brands of bullets are different. Even comparing the same type of projectile. And especially noticeable when comparing different types (FMJs to soft-points, etc.) and weights. For my bolt gun, it likes the 150s at 2.760" and the 168s at 2.80".

LDBennett · 01-16-2010, 08:04 AM

When you measure the OAL of a cartridge you don't really know how it will fit into the chamber.

The throat of the chamber is a taper down to the rifling. The bullet can have different shapes for the nose (called the Ogive). Different shaped bullet noses sink into the chamber to different depths before they hit the tapered throat. Manufacturers of bullets and reloading manuals want the bullet to NOT touch the throat so they make the bullet seat to a length that guarantees that the bullet will not touch the throat in any gun made to industry standards for that caliber.

So they make ammo OAL to accommodate the different ogives of various bullets that may have the same bullet weight.

LDBennett

01-16-2010, 12:19 AM	#1
nadroj Member Join Date: Feb 2009 Posts: 21	Need More Opinions I load cal 308 Win for an M1A. Usually use 150 gr, fmj with BLC-2 at 42 gr. Not that particular about brands of brass or projectiles. Everything that I have read says that the min case length is 2.005 and the max overall length is 2.80. I usually trim to min. case length and about 2.76 for COAL. I bought a factory box of Remington standard 308 and a box of Federal 308. The Remington measured avg 2.78 and the Federal measured avg 2.72. Maybe somebody can tell me why the big difference in COAL. Just a curious thought. As you can tell I just shoot for fun. Thank you for your opinions. -->

01-16-2010, 01:31 AM	#2
bntyhntr6975 V.I.P. Member Join Date: May 2009 Location: Wichita, Ks. Posts: 258	Re: Need More Opinions You didn't mention what projectiles were in the ammo you bought. But, keep in mind that different brands of bullets are different. Even comparing the same type of projectile. And especially noticeable when comparing different types (FMJs to soft-points, etc.) and weights. For my bolt gun, it likes the 150s at 2.760" and the 168s at 2.80". __________________ There is a fine line between paranoid and prepared.

01-16-2010, 08:04 AM	#3
LDBennett Advanced Senior Member Join Date: Dec 2003 Location: Hesperia, CA Posts: 5,711	Re: Need More Opinions When you measure the OAL of a cartridge you don't really know how it will fit into the chamber. The throat of the chamber is a taper down to the rifling. The bullet can have different shapes for the nose (called the Ogive). Different shaped bullet noses sink into the chamber to different depths before they hit the tapered throat. Manufacturers of bullets and reloading manuals want the bullet to NOT touch the throat so they make the bullet seat to a length that guarantees that the bullet will not touch the throat in any gun made to industry standards for that caliber. So they make ammo OAL to accommodate the different ogives of various bullets that may have the same bullet weight. LDBennett