Well, I finally got around to measuring the reloads that wouldn't chamber with the headspace tool. There's definitely something interesting going on.
I started by measuring some factory rounds to see where I should be. Federal 168 grain match rounds. Headspace ranged from 1.6190" to 1.6210", with most of them at 1.6205". All right, these are supposed to be awesome out-of-the-box rounds. Let's see where my reloads fell.
Measuring my reloads, I found anywhere from 1.6295" up to 1.6390". I think we've found the problem! And then the fun started when I tried to crank the resizing die down. The farthest down I could get the brass to go was 1.6220". Cranking any more than that resulted in just more resistance on the handle and no more headspace on the brass. Weird.
So on a lark... I started measuring the brass I shot a couple weekends ago, they day my reloads wouldn't chamber. This was a bunch of cheap PMC rounds, but I knew these came from my rifle. The once-fired stuff was anywhere from 1.6220" to 1.6225". Huh. So, what did that brass start out as? (measure measure measure) 1.6220".
So what we have hear is a bunch of brass that probably started out as 1.6220" and is now suddenly 1.6295"/1.62390". My conclusion after all this time on the calipers is that I have some truly funky range pickup brass. I suspect my friend's M1A1 is a bit loose in the headspace department. Apparently, this is a common "feature" of M1A1s
. A little research on the M1Forums site and I find that 1.6230" or so is typical for them.
So now the question is whether or not I can get the die to resize the brass down to 1.6220". It's taking a lot of force as it is to get the shoulder down there. I'm worried I'm going to get a case stuck.
If there is one thing a remote-controlled, silent and unseeable surveillance/killing machine needs, it’s more whimsy. -- Marcus