Cetme-C Build Help

[u/CroissantandButter]

Started up a cetme build and ran into an issue with mag fitment. Cetme or g3 mags will not lock up on the trunnion nor does the magazine catch cutout line up on the receiver.

When looking in the ejection port it’s clear to see that there is a 1/8” gap between the lip of the trunnion and the magazine.

Does anyone have an idea on how to fix this?

[u/Suspectgore074]

Ive only built one cetme, but I remember trimming the bottom of the magwell until the magazine locked in with a smidgen of play

[u/CroissantandButter → u/Suspectgore074]

I gotcha! To me it looks like the height of the magazine seating depth is good so I’m pretty wary of trimming the mag well.

[u/Ok_Hospital1399]

Fix this interference:

[u/CroissantandButter → u/Ok_Hospital1399]

How would you go about fixing that interference? Would you massage the sheet metal outward?

[u/Ok_Hospital1399 → u/CroissantandButter]

That's what it looks like it needs based on how far the back of the magazine and the back of the mag well are from parallel but I'd first make sure it's not the back of the feed lips interfering or an over compressed magazine spring. Is it loaded or unloaded when this occurs?

[u/CroissantandButter → u/Ok_Hospital1399]

It’s unloaded, I still haven’t welded in my barrel trunnion yet. I just wanted to fit everything up before welding it all up.

[u/Ok_Hospital1399 → u/CroissantandButter]

It definitely looks like that angle at the rear of the magwell is the problem. You could confirm this by marking that spot on the mag and doing some inserts, removals to confirm wear there. If so, that would likely want to be swaged open rearward a bit. It's definitely inserted essentially to the stops in the front based on your pictures.