Hi guys, I am first time poster long time lurker. I built my first ar in 300blk this year and love it. I like versatility of guns and have been trying to find a way to shoot 300blk out of a 12 gauge double barrel so I can have one barrel in 300 and the other in 12. I have seen those short chamber adaptors that only you to fire a smaller rifle or pistol cartridge. It looks like I have two options here but both seem to require mill work. I am thinking that I could either mill a 300blk barrel down to fit in the 12 bore and chamber but am unsure of alignment with firing pin and if it would even be able tosafely be milled to fit. the other option is if I got a 12g/308 over/under and got a 30Carbine chamber adaptor bored to fit the 300blk cartridge. I am more interested in the first option due to the versatility of the double in 12 and ability to use it for bird hunting. Anyone have any idea if the 300blk barrel could be fitted into the 12G chamber/barrel? If I am in the wrong forum please feel free to move it.
Thanks in advance

This is the AR Discussions forum.

I moved into the variants forum. Thanks for the help

you might have better luck here actually:

Shotgun Forum

Welcome and good luck