Khornet
and then set up my dies so that the bolt will just close snugly on the sized brass with no slop
Be
very careful in sizing brass for the gas guns. The M1 (as well as the M14 and M16 and their clones) has a floating firing pin that "pecks" the primer each time the bolt slams shut. There is a bridge in the receiver that has a slot cut for the firing pin tail which is
supposed to keep this from happening until bolt is in battery. Having sai that,
be aware that slam fires can occur due to
anything that causes the primer to be "high". Too little headspace can and
has caused such slamfires in gas guns.
A good friend, who is an experienced reloader and gas gun competitive shooter wrecked a match grade M1 at a state match a few years ago. He is a careful reloader and it took us quite a while to figure out that he had set up his dies with new brass for minimal (but safe) headspace as determined by a micrometer case gauge. The batch of brass he was firing that day had been reloaded numerous times and had work hardened and consequently it had sprung back to a larger dimension than did the new brass which caused the bolt to stop short and the slam fire.
He took a piece of schrapnel through the sweatband of his shooting cap resulting in a 1/2 cut on the forehead. His rifle had a bent op-rod, nicked the receiver where the bolt lug had barely started to close (about a 1/8" rounded corner of the receiver notch for lug), blew extractor and ejector out of bolt. Fortunately, both he and the rifle survived, but he had to work on his trigger control for a while after that incident.
I would not reload for a gas gun without a good case gauge and make it a practice to keep all my brass in lots (based on number of firings) and at least spot check every few rounds for headspace.
Nothing wrong with fitting the case to your chamber, just be sure to have ample clearances.
Regards,
hps