You have a few options.
-Buy a mark 4 with threaded barrel. Have the LGS pin weld a gemtech QDA on it before transfer. Use the qda on your can. 4 lug QD.
-Buy a preban mark and have it threaded. (Serial on upper)
-Buy a preban buckmark and swap barrels to a tacsol threaded one. ( serial is on frame )
-Buy integ. upper for a mark 4, buy a mark 4 frame online.
I recommend going preban buckmark with a tacsol or a new mark 4/buckmark/victory with a pin weld qd adapter
Deadair mask, $430+Stamp
Mark/buckmark/etc 5-600
Pin weld + qda 175-200.
I use central ct arms as they have a silencer shop kiosk and are somewhat local.
You do prints, picture, info on the kiosk, you tell them what suppressor yiu want, they’ll buy the suppressor at the shop, pay, leave. Silencer shop does the rest. You get a couple emails you need to esign, which is easy, did it on my ipotato.
I did my sandman there, did all the kiosk stuff, then I bought the Deadair mask online at home, they kept my info on file, e signed the documents, good to go.