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Intermittent ejection problems with POF P5K (Mp5 reverse stretch) 147 gr ammo

2353 Views 2 Replies 2 Participants Last post by  jimmythegeek
I'm getting stovepipes a couple of times per magazine.

It's a pretty new POF P5K with Osprey 9 suppressor. Extraction is clean, but I get internal stovepipes pretty often, around 1-4 times/magazine. By "internal" I mean they are not anywhere near the ejection port. No double feed, seems like the empty case keeps the bolt from stripping off the next round. Factory 147 grain ammo (for subsonic suppression)

Ejection is about 20 feet at 90+ degrees. I read a comment that said 45 degrees is normal/good. True?

I find when locking the bolt back on a charged mag, the live round is held by the bolt (probably the extractor) and it takes a couple of tries to get it loose.

I'd really like to stick with this ammo. With a can it's amazing.

Should I replace the ejector? HKparts says all the clones have the Gen 1 ejector and it's no bueno. Extractor? Springs? More lube? Clean it? It is pretty dirty after firing a few mags of suppressed ammo but I can't say it's getting worse or was definitely great before I got it dirty.
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Does it work okay without the can or with other ammo? You probably have too much impulse on the bolt so the extractor is slipping off. You could try a rifle extractor spring but may need a different locking piece.
I have the failures with a wide variety of 147 grain ammo. I tried without the can and still had a failure. I did not try to get a good sample to see if it happened more often with the can than without.

Another thread suggested these causes:

Most likely culprets in no particular order:

Extractor spring
bolt head (Is it in spec/oversixed? does it pass the zip tie test?)
ejector (is there much side to side play?)
trigger housing (is it parallel to the receiver or is the rear of the housing higher/lower creating an angle?)

The extractor and spring seem pretty solid. They get a good grip on the case. Too good, maybe?

I couldn't find the zip tie test, not sure how to test the bolt head.

The ejector does move side to side if I wiggle it with a finger.

The trigger housing is definitely NOT parallel to the receiver. Here's a pic showing a definite tilt: Gun Firearm Trigger Rifle Assault rifle

A new trigger pack is a little spendy. Is this unusual? Is it so obviously the problem that trying cheaper parts first is pointless? Thanks for any suggestions.

edit: I think I'll pick up a used trigger pack housing, genuine surplus HK, and move my trigger parts over to it.
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