BMP MP5K reverse stretch bolt and locking piece

Totally necro bumping this thread as it's very relevant to my current issue.

I just got an RS gun in with the 110 locking piece and am using it with the MK9K. It gassed me pretty badly with 124gr that was running sort of trans-sonic out of the gun. I still have to try some 147gr. It now looks like Germany is recommending MP5-Ks with the 100 degree part and as per Chopstix comments that looks like a good bet. My issue is that I'm probably going to run a mix of 115 unsuppressed, 124 suppressed and not, and 147 suppressed and I really don't want to go swapping locking pieces all the time.

What is my best bet for those ammo combinations? 100º or 80º.... 110º is out because I need to be able to see while shooting and the only 90º I've found is the MP5-40 which apparently does not fit... Too bad because it seems like that's the part I would want

Ronnie,

Awesome. I'll give the 100 a try and I still have to measure bolt gap. I'm hoping for a drastic change from the 110, because it was pretty awful!

I have a recoil rod similar to the BMP, might be one actually... Have you noticed a second stage stop or like a slight hold up when racking the charging handle back? Like 3/8" before the bolt is all the way back it gets a little tension I need to pull through. I had a thought it might be the recoil rod having those allen head screws on it. I might have to investigate an IGF or a cut down factory rod. It might be the carrier or something else, not sure yet. Figured I'd ask because we have similar setups, your BMP is pretty much the same as my DJ Getz gun.

Ronzo said:

Este, I did have a drag spot when racking the action back. I took my trigger box to leon at CenterMass here in Vegas and he changed out the ejector spring and the ejector axle and the action was a lot smoother. There was some crud in the ejector spring hole in the trigger box that I cleaned out with some Barnes and a Q tip. WOrks like a champ now.

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I'll try the FBI trigger pack from my fullsize, thanks!

Hmmm..... No luck on the trigger pack. I get pretty much the exact same feel with my german FBI pack and the US pack feels fine in my fullsize. I'm not sure what else it could be really...

I don't like the BMP style recoil rod AT ALL, so maybe I'll investigate that next

Ronzo said:

I really don't think the recoil rod is the culprit. You may want to try the reverse stretch recoil rod made by Dakota Tactical. Adam Weber at HKparts has them for forty dollars plus shipping.

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Wait, you don't or you do think?