I had a similar issue when upgrading to a MAD bolt head on my Omega. The factory locking piece would not even kind of fit in the MAD bolt. On a hunch that the factory locking piece was probably the issue rather than the new bolt I bought a RCM and it slid right in. I wonder if PTR and Omega are sourcing their bolts and locking pieces from the same vendor?
*edit* Just checked and my RCM locking piece fits into the Omega bolt head
Last edited by R3dundantC; 12-08-2019 at 03:35 PM.
Posted this in the suppressed thread. I'm pretty sure there are those that won't agree with my method but I am a tinkerer and and have had a bit of experience in smithing, That said, no doubt either the PTR bolt head or the RCm lp is out of spec. I suspect the former but it was an easy fix. I just need to get some -4 rollers this week to correct the wide bolt gap.
I just received a new 9KT and absolutely love it. After following this thread and reading that the pdw with brace and suppressor needed the 80* 'lp, I ordered one of the RCM parts. I use a Mk9K for suppression, btw. Installed the new lp and it was a bit tight. Found where it was binding and only had the stone a small area on the flat of the 'lp to fit it. Fit the cheaper piece, right? Harder to get inside the bolt head (more expensive part) anyway. So I get it fit, took like 5 minutes. Checked bolt gap. .026. I'm going to order a set of -4 rollers and see if that will get it back in spec....should be close. With the original 110* piece in, gap was .012 after about 500 rds.
I'll check back when I get the new rollers.
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We have been running into issues with PTR Bolt Heads lately. The walls in the pocket were the Locking Piece is located are tappered as much as .002. This is not allowing our Locking Piece to fit. I had the same issue with a factory Locking Piece too. We ground a little off to compensate for it.
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Took my RCM 80* LP and put it in my replacement KT. Since the original gap was at least .025 (and I really don't know just how high it actually was) I ordered a pair of -8 HK rollers from RTG. Got those in Friday, and today I was able to install them and check the gap again. With the new rollers, I get drag starting around .018, and significant drag at .020. Looks like the -8 rollers worked to get my gap back down to reasonable tolerances.
Lumbergh, I did not take any pics. but it is very simple. Just lay the lp flat and work the stone from the front to the rear of the wide flat several strokes, lube helps. repeat on reverse side. You can actually tap the piece in the head to "mark" it. You'll see where it needs work. Don't worry about it getting stuck, you can tap it back out. 75bronco states the inside of the head is tapered... I'm sure they are. .002 isn't much to remove.
Since I decided I didn’t want to wait a possible 4-5 week turnaround, I did the same, and tried my hand at stoning. I just stoned the two sides and it slid right in. I couldn’t turn the locking piece so I found on the round part where it was rubbing and polished it down a bit. Now it fits and turns perfectly...damn bolt gap is now at .025. The gap on the stock LP is .016. I just ordered from RTG -8 rollers to see what it does.
The -8 rollers should get you in a good area. I shot about 4 mags through mine with the .023 gap after installing -4s. No light strikes, ejection was good and it did not feel as if it was hammering the buffer. This was shooting 158gr Fiocchi subs using my old Gemtech MK-9K. With the bolt head measurements I took comparing a factory HK bolt to the PTR bolt, it could be that our gap specs are slightly broader than the factory HK specs. I still intend to play with a couple size smaller rollers (-8) just to get the gap lower. Anywho, it's looking good now. The gun is doing what it should and my assessment would concur with other positive reviews on fit, finish and function.