BudsGunShop.com - Pistol grips and braces

Brock, yes Sir, this is permissible. Just absolutely no shoulder stock as you already know.

Brock, Another birdshead grip or brace I don't know about. All I know is this AOW "Any Other Weapon" is NOT to be modified in any way then as it comes from factory.

Entering a very odd gray area with the NFA AOW/SBS laws in doing so. If you're interested in the raptor grip why not just go with the Shockwave that doesn't require a tax stamp? Since this is an AOW unlike the Shockwave you need the $200 tax stamp just to buy it but you still cannot put a stock on it because that would be an SBS. This may not answer your question particularly well but from my viewpoint, if you're going to spend 8-10 months plus $200 getting an NFA shotgun it might as well be a full blown SBS for the same price where you can use stocks, braces, pistol grips, etc. to your hearts content.