M*CARBO Brotherhood

Aftermarket SUB2000 receiver

An aftermarket SUB2000 receiver would allow the following…

A pistol build with or without brace

Possibility to take M4 style stocks and or braces

Slightly longer tube for less recoil/better buffer. For example, for length of pull I always have my stock all the way out. This means I could possibly benefit from a slightly longer receiver.

Other possibilities?



I am unsure if you would gain much reduction in recoil, but the concept does provide options.
Don’t want to be the negative guy, but you may want to consider by increasing the buffer tube will increase the over all folded length. That may impact use of current backpacks, SHTF bags, range bags or other tight space options in transportation.


If I’m not mistaken, the tube is the serialized part on the S2K. Meaning that by ATF standards, the tube is actually the firearm. So, yea, you can’t really legally change the tube out like that. This is all IF I’m not mistaken.


That would only be possible with a Gen 1 Sub2k. On the first gen sub2k, the grip frame was the serialized part. It would be possible to replace the buffer tube.
However, on the second generation sub2k, the buffer tube is the serialized part. You cannot replace it. You can replace every other part, except that one. It may be possible to weld an extension to the tube, but I don’t believe you would gain anything by doing this.

The Mcarbo buffer cushion, combined with the “recoilless” weighted charging handle, and a butt stock pad (the one made by Missouri Tactical is better than the Mcarbo pad, and easier to install) solve the felt recoil issues of the factory sub2k.