Hi Eric and welcome. Not with a Magpul Adjustable Buttstock as it would become a "Short Barreled Rifle" SBR requiring NFA registration with $200 Tax Stamp to be legal. You could use an adjustable Brace with no registration/tax stamp required. Example: budsgunshop.com/product_info.php/products_id/165735/sb+tactical+sba5x01sb+sba5+brace+black+10.25 ------------------------------------------------------- Cheers, stay safe and enjoy!

Yes, you absolutely can BUT...in doing so would classify it as an SBR which in turn would need to be Registered with the NFA. The pistol brace below is what you can use with no issues at all!!
budsgunshop.com/product_info.php/products_id/165735/sb+tactical+sba5+pistol+stabilizing+brace+-+black+mil-spec+carbine+buffer+compatible

It can be used on an AR platform pistol; however, you can't use an adjustable buttstock. Otherwise, it turns it into an SBR which will turn it into an NFA item.

Good evening to you!! You can use it on an AR platform pistol but you can't use an adjustable buttstock. Doing so turns it into a sbr which is an nfa item. Hope this helps. Have a good rest of your day.
🇺🇸🇺🇸 'Merica' 🇺🇸🇺🇸