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Posted: 5/31/2016 12:34:00 PM EDT
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Two hundred rounds or Speer 115g Lawman or 124g reloads have been used. My #1 issue is failure to fire due I believe due to light primer strikes. The weapon has fired only seven rounds before failing. Re-charge each time goes bang every time. I have also experienced double feeds, only when re charging.
Build QuarterCircle10 colt lower, Vltor upper (no forward Assist), Kaw Valley Precision 8.5 barrel, JP Bolt with JP silent capture buffer system (9MM). The trigger is self contained Wilson Combat TTU that has never been an issue in my 6.8 AR. Magazines are a mix of 32 round Metalform, ASC and 1 20 round. I noticed at range almost all my ejected non fired rounds had light primer marks and heavy scratch marks on cases. I also noticed on both sides of the trigger hammer the metal was dented. A light filing removed the issues. Pistol ejects fine and will hand cycle the mag, until last few then I get a double feed. This occurs on any brand magazine. Why did the pistol fire correctly with first mag until round 7 or 8 ? After I recharged it would fire a few times then fail. Rack shoot one or two rounds and fail to fire. During end of sesson it was only firing one round. My thinking is it is a bolt or trigger issue. The drag marks on both sides of the hammer shows it rubbing bolt. But then why will weapon fire on a recharge every time ? All parts are brand new except the trigger also. Thanks. |
| couple of suggestions... change out to a regular AR spring and buffer for a trial..... check that the firing pin return spring is installed correctly and not broken (trash in firing pin tunnel)... check the reloads that the case mouth is taper crimped, and of correct seated depth ... check that the chamber is of correct depth and that there are not burrs on the mouth... check for burrs on the bolt face so the rim of the cartridge can easily slip up the bolt face... no burrs on the firing pin hole |
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Ok just got off phone with JP. My Wilson Combat TTU is not compatible with any 9mm ramped bolt as is my Geissele Super 3 gun trigger. I figured trigger was issue due to denting of metal on the hammer and the light strikes.
Question of the day for me, what triggers are compatible with any 9mm RAMPED bolt ? |
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Installed the Hyperfire 24c as it is reported to work well in AR15 9mm. Issue is worst. Rack a round and click, nothing. Check round it has light primer strike mark same as with the Wilson Combat TTU trigger. Out of three mags 124g, 125g and 147g only had 3 rounds fire and no clue why that even happened.
I do not believe this is a trigger issue. I am going to drop in a mil spec and test again. If it fails I guess I need to take it to a pro. Really bummen 
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| Make absolutely sure that you have a firing pin spring. Try the gun with a conventional mil spec trigger. I can attest that Geissele g2s and SSA triggers work with CMMGs bolt (have two) no problem. Too light triggers will cause bumpfire or hammer follow which may cause the gun to go dead. |
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I'm having similar issues with mine. Mine keeps snapping firing pins in half causing light primer strikes. Originally had a RRA 2 Stage varmint trigger on a cmmg bolt. It was suggested to stay with a standard FCG in which I switched it out. I just broke the bolt open to clean it and found another broken firing pin. I'm interested if we could possibly having similar issues.
My parts list includes: ADCO 7 in barrel CMMG Bolt (On 3rd bolt / On about 5th or 6th firing pin) Hahn bottom loading mag block (on 2nd one) RRA 9mm buffer Wolff Xtra power buffer spring Brownells 32 rnd mags/ asc 32 rnd mags Standard GI FCG (waiting for the ALG ACT trigger to arrive) I've mostly only shot 115 gr speer lawman or federal 124 gr fmj factory ammo. Only a very few reloads mixed in. |
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My first thought would be the Firing Pin is restricted, has a spring tension issue, or is not fully reaching the primer.
If you had another bolt to try that would be my first recommendation, followed by a standard buffer spring and a 9mm buffer. You've tried enough triggers I doubt they are all causing the same issue. I've got a few hundred rounds through my Kaw Valley 4.5" barrel with no issues, so I'd hope it's not a barrel/headspace issue. Anything is possible though. |
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Quoted:
I'm having similar issues with mine. Mine keeps snapping firing pins in half causing light primer strikes. Originally had a RRA 2 Stage varmint trigger on a cmmg bolt. It was suggested to stay with a standard FCG in which I switched it out. I just broke the bolt open to clean it and found another broken firing pin. I'm interested if we could possibly having similar issues. My parts list includes: ADCO 7 in barrel CMMG Bolt (On 3rd bolt / On about 5th or 6th firing pin) Hahn bottom loading mag block (on 2nd one) RRA 9mm buffer Wolff Xtra power buffer spring Brownells 32 rnd mags/ asc 32 rnd mags Standard GI FCG (waiting for the ALG ACT trigger to arrive) I've mostly only shot 115 gr speer lawman or federal 124 gr fmj factory ammo. Only a very few reloads mixed in. GI FCG should be fine. I've run one in mine with a QC10 bolt with no issues at all. Mag block issues would be FTF, I wouldn't expect Firing Pin issues from that. Same goes for the mags. My guess is your problem is firing without being totally in battery and causing the firing pin to overextend. Maybe a Bolt or Headspace issue. First thing I would try is ditching the Xtra power spring. You shouldn't need it for a 9mm setup. Might even be causing bolt bounce.. After that I'd thoroughly inspect the bolt/barrel. |
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My gunsmith is leaning same, it is a out of battery issue. Hopefully I will hear from him tomorrow. I have not broken a firing pin, and have put almost 200 rounds most at single fire
While symptoms are close, are parts are very different. Hopefully that should not matter. |
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My gunsmith test fired my weapon. He reported that he had no issues of any kind when he fired and held weapon vertical after each shot.
No bolt spring was problem. I might have not seen spring fall out when I cleaned bolt after my first test fire, unsure (I did go over my bench area and did not locate any springs). He took bolt apart to verify also it was missing. I called JP and they are sending me a new spring, no charge ! Gunsmith does want to re test with new spring before calling it good. Sounds like the Wilson Combat TTU was not compatible, the Hyperfire 24c is and only failed due to lack of bolt spring so that is good news for me. Thanks everyone for the advice. |
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Yep I could have sworn when I first received the bolt the firing pin was installed, but I did not take it apart. On the other hand when I did strip it I did not notice a spring and I have searched several times. Who knows ? Good is JP sent me another without charge even after I stated I might have lost it !
Hopefully this is only issue and next week I will be banging out rounds 
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Fixed !!!! Runs without issue and very very fast firing. It was in fact a missing firing pin spring and the Wilson Combat TTU trigger were issues.
Switched to the Hyperfire 24c added the spring and it ran like a clock. Three hundred rounds all mixed weight or bullet (all reloads), three different magazine brands nothing stopped it from spitting rounds. |
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Quoted:
Issue Was The Missing Firing Pin Spring. Once added gun ran like a champ. The Hyperfire 24c is super fast firing, very smooth trigger. I doubt the previous trigger kept the gun from operating properly, but I'll bet the fancy Hyperfire trigger makes a working 9mm gun a lot more fun to shoot! Congratulations on the fix and solving the puzzle. |
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