Failure to feed malf; only when loading
I have an oddball malf with one carbine. I am trying to isolate the problem. Here's the hardware:
BCM midlength 16" ltwt upper
Semi-auto BCG (either LMT or Denny's)
Op spring in is spec, fewer than 1000 rounds
H buffer
Colt carbine lower (with sear block); I installed the carbine RE
Federal M193 cartridges
USGI mags that have fit and functioned with other carbine setups
Lube is Mobile One 10-30
Sometimes during testing the BCG will go forward quickly, other times it seems sluggish. No apparent rhyme or reason to it. I have pulled the spring out and checked for problems, measured it, and it seems fine.
Malf only happens on loading from a partially full magazine. Never has happened when shooting, only loading. In this case, cartridge will be pushed about 1" forward, then stop. (Have not noted if it is in contact with feed ramps.) Usually happens during the middle of a shooting session, when I put the carbine down for 10 minutes or so, then try to resume shooting. Outside temperature is about 35-40 degrees.
In my mind it could be:
BCG (although it ran well on a different lower)
Spring
Sear block (yeah, I know, it's on my list of things to get rid of)
Lube in cold temperatures
To isolate the problem, I am considering running the upper on a different lower, running the upper on a different lower (but, using the same spring and buffer as with the malfs), changing the spring, changing lube, changing BCG. Any ideas?
Last edited by Amicus; 12-20-11 at 17:45.
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