45 ACP Gas Operated Upper

45 ACP Gas Operated Upper by RMW
10″ barrel, Gemtech Blackside used in first part of video:

The gas operated 45′s need as much gas as they can get. Gas port is as large as possible. .125″ is max diameter of a gas tube. You can see the gas block under the handguard right in front of the barrel nut.
I had Young Manufacturing make me custom lightened M16 spec carriers (to work with RDIAS). You can always tune the mass with buffers. Although after more testing, it seemed that a normal M16 carrier worked but not as smooth as the Young carrier with the lighter weight.
Note how deep the catch is going into the magwell. Unmodified, the MGI 45 GG magwell wouldn’t engage the GG mags enough so they would fall out when firing.
Note that I cut notches in the front of the feed lips of the GG mags. I had feeding issues so by doing this, the back end of the round would be able get out of the mag earlier.
Bolt used is a 450 Bushmaster bolt. Ron also modified the face of the ejector I guess to change the ejection pattern but I changed to a different ejector and didn’t really notice any difference.
45Upper-mags-magwell

The MGI GG magwell doesn’t come with the bolt hold open functionality so I had a friend drill into the magwell and mill the slot for the bolt hold open spring. Of course the GG mags won’t hold the bolt back after the last round. I just wanted to be able to manually hold the bolt back. Worked great.
45-MGI-GG-4

Modified mag catch so it would go deeper into the GG’s notch
45MGI-mod

45Upper-mod