u/Spilt_Beanz · 2022-05-10 20:09:03 UTC · score 1

Correct I understand the intention of the design but in practice it doesn’t work with 5.56 uppers. The hammer needs to go down far enough so that the BCG doesn’t bind on the return.

I’m still trying to fully understand some parts of the design though. The auto trip is the lowest part of the BCG. There’…

u/irony-identifier-bot · 2025-02-20 16:42:37 UTC · score 3

My UMP 11/9 upper remix. I changed quite a few things. Removed sights and replaced it with a full rail, changed the rear plate to match top rail, fixed the ejection port geometry, redesigned the handguard cover, removed logos, made the front face vertical.

u/tavelkyosoba · 2022-05-10 20:41:26 UTC · score 1

Many people have independently tested this for function with 5.56 uppers. The issue you're describing is caused by the hammer spur not pushing the plate down far enough.

(The bcg doesn't push the cam down far enough to disengage. )

Now, it has to catch on the channel because the little pocket on…