[Steve Smith]

There are two types of full length sizers. One is commonly referred to as a "Full length sizer" and the otehr is referred to as a "Small Base sizer." The small base, is, guess what...smaller.

I'll bet we're all using full length size dies (I know a few guys that just use neck dies for their AR's, but they're rare) but only one guy, John Marshall, is using a small base. IMHO, I think he's working his brass more than he needs to.

As you go along, you may even want to set your die so that it works the brass the least. You'll be setting it to be just a tiny bit smaller than the max headspace measurement...but that's a different thread.