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Joined: Jan 2022
10-05-2022, 08:17 PM
(This post was last modified: 10-05-2022, 08:29 PM by pmc847.)
Help!
Having ejector problem, bolt only partially locking back, locking on front of bolt carrier not the bolt.
Rifle +2 gas block (Superlative adj) set wide open 18 clicks out.
JP 6.5 Grendel bolt
JP SCS gen 2 buffer black spring
Extended bolt release
Craddock Bartlien 6mm ARC 26” 7.25 twist
Using Hornady 105 black or 108 match
Emailed JP twice, no response
Any help will be appreciated.
Works just fine with 223 Wilde upper.
Cheers
Philip
Posts: 842
Threads: 35
Joined: Jun 2020
You'll probably need to eliminate any non-standard components in order to simplify the problem.
First off, to me, 26" and a +2 gas port means 2 things to me: plug dwell time is still pretty long but gas pressure for cycling will be low, and relatively late. Compared to a 20". Cmmg does their 20" at +1 or 2 IIRC.
I'd recommend you first of all, take out the SCS and black spring and put in standard carbine buffer and standard carbine spring. standard bolt carrier also. Assuming carbine stock. If it's a rifle stock then you need to use an internal buffer tube shortener and carbine weight/spring, the rifle 5.3 oz weight might be too heavy.
If that does not resolve the issue, you'll probably need to look into enlarging the gas port diameter, this can be done but you have to be careful. I can give some pointers if you get to that.
As long as the chamber itself is not rough or anything, best guess is way under-gassed.
Posts: 37
Threads: 10
Joined: Jan 2022
I will try the stock setup. Good info and thanks for you help. Will post results.
Posts: 37
Threads: 10
Joined: Jan 2022
11-10-2022, 08:22 PM
(This post was last modified: 11-10-2022, 08:23 PM by pmc847.)
Fixed.
I tried a lighter spring in the PJ SCS buffer, no change.
went back to stock buffer set up, no change.
Started removing weights from buffer and by the time I got to 0 weights (just the rifle length buffer) it works.
I will still use the JP SCS when 223 upper is attached.
Very touchy setup when shooting 6 ARC with +2 gas.
Now on to load development.
Cheers
Philip
Posts: 842
Threads: 35
Joined: Jun 2020
Kind of what I figured. That rifle buffer is too heavy. I had/have a couple rifle stocks, but in them I first load in a poly "buffer shortener" (I forget the actual term. Then a carbine length spring and buffer will work. (Carbine SCS too if that's your fancy.) And that same gear would work for the 223W upper too. But if it's working for you, load shoot and be safe.
