Feeding issues [Archive] - Glock Talk

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madecov
07-05-2010, 20:50
Home built rifle

Quality upper and lower

Superior Arms 18" 1:8 barrel (Lothar Walther) wylde chamber, rifle length gas system

Midwest industry gas block

DPMS tube

CMT Bolt carrier/matched bolt supplied with barrel

Gun will not feed from a locked back bolt with any magazine
Gun will sometimes feed when cycled using the charging handle.
Gun will sometimes feed 7-8 rounds through magazine but never a full magazine and rarely the last round in the magazine.

Gun will fire and extract reliably when feeding and does lock back when fed a single round

I've tried swapping bolts/carriers/bolt and carrier/lowers and can't diagnose the problem.

Any thoughts

Constructor
07-08-2010, 02:00
Are the mag lips rubbing the bottom of the carrier? It sounds like something is slowing the carrier movement, you may need a stronger op/buffer spring like a SSS or "Tactical Springs" buffer spring to shove the carrier forward but in doing so there may not be enough gas to push the carrier back so the gas port may need to be opened slightly. An 18" barrel with a rifle gas may need a .083-.086 gas port. but always enlarge a few thou at a time and check lock back after every enlargement.

madecov
07-08-2010, 08:59
This happens with every magazine. P-mags, GI, Brownells, C-products

I'm using a standard buffer and spring.

I have no idea of the gas port size