didn't have time to put the barrel on...but screwed it on hand tight and got worried. About half an inch to close the witness marks together! The Sarco "NOS" barrel goes back tomorrow, but hand-snugs up to ~.2. The first one was the same, and I had it torqued on and aligned no problem.
What's the difference? I'm glad you asked. My NOS 2-groove has very heavy and rough parkerizing, all intact and pristine, all over the threads and shoulder. The Sarco "NOS" 4-groove has worn smooth, light parkerizing, hardly any left on the bottom couple of threads, and some dings on the edge of the cone. The first one they sent me was the same. I'm very convinced these Sarco "NOS" barrels came off of rifles. The original barrel snugs up hand tight to just under 1/8inch, and its threads are blued and smooth. I think it's all in the variances in finish.
I'll clean up the parkerizing on the threads and shoulder of my new barrel with a fine wire brush or fine wheel on a dremmel. Should do the trick, but I'm a bit nervous. I just finally shelled out for a reamer and handle...no more rentals, and now I might just have to send this out to get the shoulder pushed back - costs next to nothing more to have it finished reamed on the lathe.