The mystery of why my carbine wont lock back

[washguy]

Hi Guys  well ive been keeping a secret from you all while I worked for weeks on this problem of a car not locking back and therefor causing ftf's and fte's with a case sticking in the chamber mostly

Yes after 25 of building ar's I built one that wouldnt lock back....and of course it had to be the Mega monolithic 6.8 <laughs>

when it happened first time out my jaw hit the bench!

polishing the chamber....nope

changing bcg.....nope

checking gas port size...perfect

gas block even changed em out...no bueno

changed out buffers,springs....nope

different ammo ...nope

here's where im embarresed....Harrison said send the upper to him even though i only bought the barrel from him...now thats service beyond!

Harrison sez upper works fine...sends it back

while the upper is on its way back i get a flash in my mind of BayouBobs problemo with his cmmg car that wouldnt work until one day they sent him his car back with a a2 stock on it and it worked fine.....hmmmmm

Here's where the problem is...and maybe just maybe why there are short stroke problems for the guys!

I take off a buffer tube of a car that works fine

inside length 7"

I take off the buffer tube off the lower that wont work

inside length 6 3/4 "

put a new 7" buffer tube on the mega 6.8....works like a champ!  the 3/4" short buffer was causing the cycling problems! :) Wash

buffer tube that short strokes

buffer tube that works fine

[unforgiven]

Confession is good for the soul.Don't you feel better now brother Jeff <lmao> <laughs> What other dark secreats are you hiding,we don't judge. :o <lmao>

[Robocop1051]

What kind of buffer are you using in that? I believe they make a shorter buffer for those shorter tube.

[washguy]

What kind of buffer are you using in that? I believe they make a shorter buffer for those shorter tube.

Robo  thats my point. The buffer tube is a standard buffer tube ..actually they are both standard 5/6 position buffer tubes.....I used a standard car buffer in the faulty one, and tried various h2's h3's buffers

what im saying is ...the short buffer tube is a machining mistake by over 3/4 of an inch...its not that its sold as a short buffer tube....its a mistake that costs people time and effort to try to find out what may be causing a short stroke problem...I had eliminated every possible part that was causing the lock back problem....it came down to a mis machined no name cheap buffer tube

:) Wash

[Robocop1051]

Damn it Wash! Quit wasting good ammo money on faulty buffer tubes! :bat: