I've read with great interest the many and lengthy posts regarding PTR91's and their problem with tar sealed milsurp. As an owner of an early AW example, I wanted to find out if my rifle would handle milsurp, so I decided to do my own test with some South African R1M1 I picked up locally.
PTR91F 18", AW01 serial number, 12 flutes, bolt gap has held steady at 0.145.
Rifle was delivered with an HK bolt carrier and HK bolt head, and I think non-HK locking piece.
I do not have an exact round count, but certainly under 500 rounds so far; all ammo has been "commercial", mostly Federal and BVAC once fired brass. I have yet to experience any problems with the rifle.
Changes made before testing:
I added a real HK butt stock, with the properly mounted recoil buffer (greatly reduced felt recoil)
I added a new HK locking piece
Addition of HK wide forearm with bi-pod
Hendsolt z24 scope
Otherwise, the rifle is as delivered from PTR.
I gave the rifle a thorough cleaning, as I normally do, and paid a little extra attention to chamber and roller recesses.
Packed up my gear, 140 rounds of SA R1M1, 4 large pumpkins and 20 small ones (about the size of a softball), and headed to my favorite outdoor range. Weather at the range was scrappy -- windy, raining constantly, and with temps ranging from the 40's to low 50's.
I loaded up one mag with 20 rounds -- at first I had only put 10 in the mag, thinking I'd never make it through all 10 much less 20. Sited on a big pumpkin 100 yards down range, and popped of a round which hit home, and another, and another, and another…made it through all 20, no problems at all. I waited a few seconds to a few mins between shots. Ejection was just like with commercial -- violent, flinging brass 20+ feet to the right.
Load up more mags, and varied shooting speed from slow and controlled all the way to a full mag dump more or less as fast as I could manage. In al,l I put 100 rounds of the SA the the PTR with no problems at all. Accuracy with the R1M1 was quite good; at 100 yards I was regularly hitting the small pumpkins, usually on the first shot.
I have a local resource with quite a bit more SA and think I will grab all he has!
Good day for the PTR, bad day to be a pumpkin!
Hope the info proves helpful.