Originally Posted by Jim K
What you do is turn the piston nut (the castle nut with three projections) in until the bottom of the cuts is even with the edge of the cylinder, then use a center punch to stake the nut in place by punching the nut at the edge so some metal pushes outward and locks the nut in place. Some folks use blue Loctite. But you don't screw that nut down as far as you can, because the piston won't have enough movement to function the carbine.
You should have (or buy) a piston nut wrench, which is the proper and best tool for working on that nut.
I gave it the old eye ball inspection and here's what I found. The nut is the type 2 that is countersunk .030 in. for more piston travel, but I can't see anywhere that its ever been staked. The nut turns a bit over one turn from flush and gets tight, I'm guessing .005 - .010 in. past flush. I know that my Uncle bought it through the NRA for $25.00 back in early to mid 50's. I've had one person tell me they did away with the staking process when they came out with the new style nuts. My plan is to use a drop of locktite anyway, but I'm not sure if I should snug it down or make it flush since it already has .030 in. more travel. The barrel is an IBM CORP W/O any date, the receiver is a late production # for a Postal Meter but I realize the barrel may have been changed before it went to the NRA. Would leaving it flush hurt anything with the longer travel? This is my first M1, but since it was my late Uncles I my be a little over cautious, if you know what I mean. LOL Anyway anything I can learn is GREATLY APPRECIATED! Thanks Again.
BTW a 11/32in. 1/4in. drive 6 point socket is quick & easy to modify with a dremmel & cutoff wheel if you don't want to wait on shipping, just take it slow and you can make it fit perfect, just use the 6 points as a guide on where to cut.