I built an AR Pistol with a 11.5 barrel, my understanding if it's total length is 26' or longer I can use it like a rifle and ATF does not consider it
Del-Ton, Inc. AR-15 11.5" Pistol Kit
Best AR Pistol Barrel Length | CarolinaFirearmsForum
GlockGuy226 - What's Your Favorite AR15 Pistol Barrel Length? 🤔 This Is An 11.5" Barrel On A Build I Did A Few Years Back! ☠ I personally Like 11.5" Or 10.5" Barrels