I am thinking of building an AR-15 upper in 458 SOCOM. I was going to go with a Tromix 12" lightweight barrel and bolt combo and run it on a pistol lower. Considering the potential re-classing of AR pistols, should I go with 16" barrel and play it safe or go with 12" and let the AFT pound sand?

I don’t have one so speaking from limited experience here but I was just shooting a buddies 458 SOCOM and another guys 450 Bushmaster a few weeks ago comparing them. I would build a rifle so I could get a nice recoil pad on the butt stock and consider a fixed stock or a really solid adjustable. I don’t think going light weight would be my priority. Either way you’re going to have fun with them but a little bigger gun might be more enjoyable on the range.

That sounds reasonable. A pistol brace may not handle the punch.

It just seems that these assault pistols with braces are going to be the lowest hanging fruit for an ATF with new leadership and new marching orders. Build the long gun.

If you shot a SOCOM and still think it kicks don't ever shoot a high brass 20 gauge 3". You may not live through it! I have shot 285 gr cast and 500 gr FMJs and several in between and didn't feel all that much recoil. And I'm barely over 5'1". Those pistols in a folding brace are a great truck gun. Mine has a 10.5" barrel and I'm lining up to get a suppressor. It can be pinned if the ATF gets too frisky. Be Well, RZ.