Small Base dies vs. FL dies

[StraitShooter]

While I am a new member, I have been reading this forum for over a year and I'm very impressed by the knowledge base here. Recently, I've been reloading .223REM for my wife's AR-15 which is used in the CMP, as well as for my M1A. In various places I have read that autoloaders should use small base sizing dies, but I have also read that a regular full length sizer should be used so as not to create excess headspace. I hope that one or more of you has an opinion or can discuss this subject. Thanks in advance.

Eric

 

[Preacher]

Auto loaders don't have the camming power that a bolt gun has, so they need to be sure the base is not to large, so they use a small base die.
Either die needs to be set up so you don't run into a headspace problem...
Set the dies up for her rifle, not what the instructions say, and you'll be good..

 

[spclark]

Careful using .223REM in your M1A friend :lol: as they don't usually play well together....

Whether for an AR-15 or an M1A, the goal is to return fired case dimensions to a size that permits smooth chambering. Depending on your rifle's chamber dimensions, the brass you use, and the relative power of the loads you shoot, small-base dies may be needed but typically aren't necessary; a full length sizing die should work once it's properly set up. The bolt in a rifle shouldn't be doing the work of your reloading press!

Typical gas gun shoulder "bump" is .003" - .005".

With either type of case die - and both .223REM or .308 WIN - it's important to move the case shoulder back far enough for smooth chambering, but not too much. Moving it back too far causes an excessive headspace condition & can be downright dangerous.

A good test is to break down the rifle you're sizing brass for & see if you can easily chamber a sized case. Move the case shoulder back just enough to let the bolt close & lock smoothly under hand pressure alone & you should be OK.

 

[fdshuster]

StraitShooter: A really helpful book,, I believe), for everything you could want to know about the AR-15 is "The Competitive AR-15", by Glen D. Zediker, in softcover, available from Midway, Sinclair, etc. 286 pages with articles by several very knowledgable individuals,Derrick Martin, G.David Tubb, etc.). A lot of emphasis on reloading requirements for the "gas gun".

 

[StraitShooter]

Thanks Preacher,
I think I understand your communication: as long as the resized brass chambers easily,proper headspace), it doesn't really matter if I use a normal or a small base die. Did I get that right?
Thanks again for your insight.

 

[StraitShooter]

spclark, In kindergarten I was ver good at putting the round peg in the square hole. Now I know why that .308 wouldn't chamber in the AR.
Seriously, your post was extremely helpful.

Fdshuster: why would I want to get that book for my wife, she's already a better shot than I. She has seen it and was thinking about getting it. Now that I know there's a lot on reloading, I'll get it for her for Valentine's Day.

 

[Innovative]

StraightShooter,

It is possible to determine,for sure) if you need to use a small base die or not. I've made an inexpensive Digital Headspace Gauge that measures the chamber clearance that your handloads will have in YOUR particular chamber. Check it out on my website.

- Innovative