I just picked up a MCX hybrid lower, which I believe is a m400 standard lower with the MCX adapter. I’m trying to get the adapter off to put it on a registered lower so I can throw my rattler upper on there.

I’m able to get the outer half of the adapter off, but the part that actually threads into the lower won’t budge

Does anyone have any experience with removing one of these adapters?

Thanks for any advice in advance!

quote:

Originally posted by Flgorilla18:
I just picked up a MCX hybrid lower, which I believe is a m400 standard lower with the MCX adapter. I’m trying to get the adapter off to put it on a registered lower so I can throw my rattler upper on there.

I’m able to get the outer half of the adapter off, but the part that actually threads into the lower won’t budge

Does anyone have any experience with removing one of these adapters?

Thanks for any advice in advance!

They probably used Loctite of some kind, since the adapter threads into the buffer tube threads. Try heating it up a bit and then give it another try.

It's also possible they used Rockset, which withstands hear. To loosen Rockset you need to soak in warm water for a few hours and then give it a twist.
Good luck!

I have a RRA upper I bought years ago and wanted to switch out the tubular hand guard to a YHM quad rail. I could not get that thing off for the life of me. I am not sure what they used at the factory to put it on but I wound up taking it to a local smith who was able to get it off. I spoke to him afterwards and he said don't ever bring back another one of those things again. I had to laugh but I knew what he went through as I tried many things to get it off myself to no avail. Heat seems to work but I am always a little leery about doing it myself.