Falcon Industries/ERGO brings this receiver extension castle nut for M4 style receiver extension tubes.
More...
Customer ratings for ERGO GRIPS AR-15/M16 M4 RECEIVER CASTLE NUT
Number of ratings: 2
From brownells.com: 2
Average rating: 5
Good Castle Nut (16/05/2017)
Good Nut, Correct Dimensions, Has the spots for the stacking from the endplate to enter, fits with a standard armorers wrench, tough, finish is even and strong. Great product would be a second when I need another.
Solid USA Product(05/12/2017)
Castle nut has a standard mil-spec finish, has stake pockets which gives you the option and the front to back width measures 0.375" unlike other products which measure 0.3" wide.
Falcon Industries/ERGO brings this receiver extension castle nut for M4 style receiver extension tubes.
More...
Customer ratings for ERGO GRIPS AR-15/M16 M4 RECEIVER CASTLE NUT
Number of ratings: 2
From brownells.com: 2
Average rating: 5
Good Castle Nut (16/05/2017)
Good Nut, Correct Dimensions, Has the spots for the stacking from the endplate to enter, fits with a standard armorers wrench, tough, finish is even and strong. Great product would be a second when I need another.
Solid USA Product(05/12/2017)
Castle nut has a standard mil-spec finish, has stake pockets which gives you the option and the front to back width measures 0.375" unlike other products which measure 0.3" wide.