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JimDandy · November 4, 2013, 02:10 AM

Most of the books and manuals do say for an auto loader you can't neck size, and must FL size. Someone previously suggested a middle ground. That's up to you and your comfort level.

The .223/5.56 has at least three chambers, and multitudinous riflings. Bullet weight range is also fairly extreme. From sub-50 grain bullets to 90 or more. AR barrels are USUALLY rifled 1-9 to 1-7. The rate of the twist will determine your max bullet weight, and will also affect performance for a minimum bullet weight and design.

There is some fear that a faster 1-7 rifling will cause lighter varmint rounds to destabilize and fail in flight with the varmint jacket peeling off or some such.

I don't worry about slamfires, but if I saw the AR primers on the shelf, I'd buy them. Just because I don't worry about them doesn't mean I won't take extra free or nearly free peace of mind.

I wouldn't "crimp" any 223 or 5.56 unless there's a cannelure. I probably won't even crimp the 55 grain Hornady's with a cannelure I picked up. When you size your brass, trim, chamfer and deburr, that should have enough neck tension to hold the bullet for you, even in an auto loader.

I have a 1-7. I shoot factory 55 grain FMJ's for brass, and reload them with Nosler Custom Competition 69 and 77 grain FJ-BT's over RL-15.

November 4, 2013, 02:10 AM	#6
JimDandy Senior Member Join Date: August 8, 2012 Posts: 2,556	Most of the books and manuals do say for an auto loader you can't neck size, and must FL size. Someone previously suggested a middle ground. That's up to you and your comfort level. The .223/5.56 has at least three chambers, and multitudinous riflings. Bullet weight range is also fairly extreme. From sub-50 grain bullets to 90 or more. AR barrels are USUALLY rifled 1-9 to 1-7. The rate of the twist will determine your max bullet weight, and will also affect performance for a minimum bullet weight and design. There is some fear that a faster 1-7 rifling will cause lighter varmint rounds to destabilize and fail in flight with the varmint jacket peeling off or some such. I don't worry about slamfires, but if I saw the AR primers on the shelf, I'd buy them. Just because I don't worry about them doesn't mean I won't take extra free or nearly free peace of mind. I wouldn't "crimp" any 223 or 5.56 unless there's a cannelure. I probably won't even crimp the 55 grain Hornady's with a cannelure I picked up. When you size your brass, trim, chamfer and deburr, that should have enough neck tension to hold the bullet for you, even in an auto loader. I have a 1-7. I shoot factory 55 grain FMJ's for brass, and reload them with Nosler Custom Competition 69 and 77 grain FJ-BT's over RL-15.