HKPRO Forums banner

1 - 17 of 17 Posts

·
Registered
Joined
·
6 Posts
Discussion Starter #1
Hey everyone, I've got a Coharie Arms MP510mm that I SBRd years ago, but have always had ejection problems. Originally the problem was that the case would not fully clear the port and the bolt would start to close forcing the mouth of the case against the forward edge of the port and shred it before finally flinging it clear. It would still feed and fire, but messy. Also, the last case would never be ejected and would just lay on top of the empty mag. I have swapped out the ejector for a genuine German version, but then I started having problems with the ejector getting caught under the bolt rather than riding in the groove. I've tweaked it a bit and it's better, but not perfect. I'm also getting lots of failures to eject. I'm needing some professional help. Suggestions on a gunsmith who can help me with this?
 

·
Registered
Joined
·
597 Posts
I had the same problem with my .40. My bolt was “floppy” on the locking piece. Sometimes it worked great and other times would do the same thing you are describing.
I started replacing parts with real HK. But due to not fitting, eventually the entire bolt carrier group was replaced with genuine HK and all the problems went away.
My bolt moves very linear with no more wobble now
 

·
Registered
Joined
·
6 Posts
Discussion Starter #6
I had the same problem with my .40. My bolt was “floppy” on the locking piece. Sometimes it worked great and other times would do the same thing you are describing.
I started replacing parts with real HK. But due to not fitting, eventually the entire bolt carrier group was replaced with genuine HK and all the problems went away.
My bolt moves very linear with no more wobble now
Is your .40 a Coharie Arms?
 

·
Premium Member
Joined
·
218 Posts
I have a Getz build, replaced the bolt group and ejector with HK and RCM. Try replacing the extractor spring with the gold 9mm version. There is a .40/10mm specific version, but not available from what I have seen. Install a HK ejector as well.
Bill
 

·
Registered
Joined
·
6 Posts
Discussion Starter #9
What's the word on RCM parts? I was checking HKParts.net and they're currently out of German bolts (and may not get any more by the sound of it). I can get a complete RCM carrier group for a little over $400, but don't want to replace bad parts with more bad parts. Opinions?
 

·
Registered
Joined
·
6 Posts
Discussion Starter #12
So I purchased a complete bolt group from RCM and dropped it in. Almost a little too tight! When working the action I was still having the same problem of the ejector getting caught under the bolt. I grabbed my PTR G3K and removed the trigger pack, swapped out the ejector, and presto!... no more problem with the ejector hanging up. Took it out back and ran a box of ammo through it. I had a couple double feeds early on, but I did notice the 10mm ejector was a bit stiff in the G3 trigger pack so maybe that was adding to the mix. By the end though, I was running five shot strings through the gun with no problems. Looks like I need a new trigger pack. Found an HK94 semi trigger pack on RTGParts.com, but currently out of stock. Any other places I should look?
 

·
Registered
Joined
·
597 Posts
Make sure the difference between trigger packs isn’t just how high it sits. I had a 9mm clone that needed the trigger pack shimmed up to work. My sear pack always worked perfectly though.
 

·
Registered
Joined
·
6 Posts
Discussion Starter #14
Make sure the difference between trigger packs isn’t just how high it sits. I had a 9mm clone that needed the trigger pack shimmed up to work. My sear pack always worked perfectly though.
Good tip. What did you use to shim the pack?
 

·
Registered
Joined
·
597 Posts
I was building aircraft at the time, we had various thickness aluminum shims at the shop, I think I epoxied them all to the shelf of the trigger box when I got the right height.
 

·
Registered
Joined
·
902 Posts
If your ejector is binding your bolt your denial is causing your lower/ trigger pack to sit too high. OR your lower/ trigger pack is set for a different denial height) You can either adjust the lower by filing or milling or file the top of the denial to get the correct height. Look along both sides of the pack to see if the gap between the lower and reciever is uniform. That might give you a visual clue. Also verify your ejector is recessing in the channel under the bolt.
 
1 - 17 of 17 Posts
Top