I have a used JP Enterprises Recoil Eliminator (Tank Brake) for sale...
I paid $90.00 for it & am asking $50.00 shipped (plus I'll throw in one of my Tactical Slings for free).
This brake is designed to fit on post ban rifles
. It uses an unusual thread pitch... I believe its 5/8 x 36 tpi...
It does an awsome job on eliminating the muzzle rise & felt recoil on .223 AR15's !
Email if interested: firstname.lastname@example.org