New Magpul UBR-2 bolt not locking back on PMAGS
I have emailed Magpul and will call later today. Love Magpul, but would love to hear any ideas here to for sake of knowledge...
Rifle functioned perfectly with ALL mag types before install.
Build is Noveske Gen 3 Lower, VLTOR MUR-1A upper, Noveske CL 16" Mid barrel, Geissele LPK, Geissele Trig, Noveske BCG, VLTOR A5-H2 RE... runs perfect!
Added UBR-2 with A5-H2 system and setup without tube spacer as directions advise.
All GI mags GTG, ALL PMags fail to lock back.
I do not believe this is a PMAG problem
A. I'm guessing either the UBR's tube is different length and is causing this...
B. Is this a tube problem or is this gonna be a buffer weight problem? or?
C. Is this causing an over or under gassed situation/over sprung or undersprung?
New Magpul UBR-2 bolt not locking back on PMAGS
Quote:
Originally Posted by
M4Fundi
The BCG locks back perfectly manually on both GI & Pmags... i swapped BCG , CH, complete upper, lowers and manually all is GTG.
Only when firing with Pmags does it not lock back.
VLTOR has me taking measurements next week and
Magpul says that it MUST be a gas issue and that either the bolt gas rings or poor ammo is to blame
Ill check next week when i get back
I experienced the same issue on my UBR 2 setup. 12" LaRue barrel, A5H2 buffer standard A5 spring, LMT FA BCG. I noticed it on Gen2 and Gen 3 windowed PMAGS. I didn't try my Lancer or USGI. I thought it might be a new ammo but after thinking more on it I am positive I shot this ammo prior to the UBR 2.0 without any issues. Left me scratching my head, but I didn't have time to start swapping out parts. That same training day I was running that ammo in my 11.5 SBR but with a DD barrel, A5 tube, enhanced LMT FA Bolt Carrier w/standard LMT bolt.
I tend to agree with IG. Nothing in my 12" SBR is old enough to be worn out, the UBR 2 is the only change introduced to my setup.
I did an eyeball compare of the UBR tube and the A5 (Vltor) I pulled off and they appeared to be right st the same length. Could have been a small variance I suppose.
Not sure I agree with Magpul's assessment because my BCG has a pretty low round count and it all worked as advertised two weeks ago when it wore a SL-S stock on an A5 tube.
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New Magpul UBR-2 bolt not locking back on PMAGS
I'll test mine out today. I haven't used a pmag with it. The lancer has been flawless.
ETA: After testing, 30rd gen 2 and 10-20-30 round gen 3 pmags work well with mine with manual cycling. I'm running the A5 system.