Originally Posted by
SPQR476
There are some threads on here and definitely on the HkCentric forum if search here doesn't work that walk down the whole JLD/PTR timeline and address what serial numbers are what with known issues. Some A-prefix guns had tight chambers, but most work fine. Very early AW guns are fine, but the switch to TC barrels with shallow flutes around AW1500-200 or so caused issues with any tar-sealed ammo, which includes South African, Radway, Paki, DAG, and a bunch of others, including US made M852 and special ball. After blaming the issue on underpowered ammo for years, they went back to correct flute geometry with the GI model and across the line shortly after. All current barrels are GTG. As German parts dried up and domestic manufacture had to pick up the slack, there were some initial hardness issues with both bolts and trunnions. PTR replaced all cracked bolts or trunnions and eventually sorted out the metallurgy. There was a pretty good write up on one of the more manufacturing and engineering centric forums about cross sectioned hardness of PTR, RCM, and HK components, and it seemed the latest stuff is quite good. Anything after AW8376 or so and any new GIs should be fine.
From a practical side, I have 5 PTRs. 2 that had shallow flutes. One wears an RCM k barrel now, the other is a DMR and kept the TC barrel since it's a sub MOA roller locker and I didn't have the heart to change the bbl. out. One GI, which cracked the trunnion as one of the hardness problem guns, PTR fixed that in a week turn, and it's been fine since. 2 are late production guns, Post AW8376 or so for an MSG91 in battle rifle trim and a 16" GI with a full length cocking tube. I recently acquired the second GI and don't have time on it, but the MSG91 has been trouble free.
If they don't have welded rails, they have MFI mounts bedded, but not glued, to the receivers with steel bed. All except the DMR with shallow flutes shoot all ammo just fine, including tar sealed and steel cased. The DMR runs suppressed most of the time with a #17 locking piece and a single stage heavy buffer. All have real paddle releases added. Just bite the bullet and get it done, it's the way the rifle was intended to be run. The heavy buffers from Ghilliebear are GTG...he makes them by welding two stock buffer bodies together, turning a new piston and adding a new spring pack. They are also a lot cheaper than real heavy buffers and easier to fit in most stocks. The ESSL type SEF levers are useful...I have no problem with the selector unless I'm prone, but then the extended helps. YMMV.
While they are cheap, pick up extractors, extractor springs (You'll likely ruin one or two of these detail cleaning over the years), ejectors, firing pin and spring, and a recoil spring or two. If you are going to mess with the trigger at all, pick up an extra hammer and sear. Then...Rollers... +2, +4, +8 are in my stash, along with retainer plates and pins. I have a ton of stuff, but it's because I'm a roller gun nerd, not because I really need it.
I got into these years ago, when commercially available 7.62 AR variants were dubious, at best. I like roller guns, but if I were starting over, I'd probably have a couple to play with and be more heavy on SCAR or AR variants in 7.62. My G3k clone, though, is one of my favorites, and just a fun gun that is rather effective.
Mags aren't 99 cents anymore like when I bought most of mine, but they are still so cheap that it just doesn't make sense for us to bother making one. The gun is pretty forgiving as far as feeding, and I can't say I've ever had a failure to feed, even from really messed up mags. It's a big gaping hole to hit and an enormous bolt carrier slamming the rounds home, so it works. The BCG would likely also make a highly effective melee weapon. :-)
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