I plan on putting a Enforcer pistol (cut-down .30 carbine) into a GI-type side folding stock along with some minor sight mods..

The Enforcer's receiver is already registered as a pistol.

What forms do I need to get a stamp before doing the mods? 1140-0011 (making a firearm)?

Will it need to be engraved?

Thanks.

BTW....This will not be through a trust. Individual with LEO sign-off. I've done a form 4 for my can some years ago so I know how that part works.

So basically you're making a SBR?

In that case just a Form 1