Cross Armory Flop Stop + Pin Pal Black Melonite 4140 Steel AR-15/M16/M4

The Cross Armory Flop Stop + Pin Pal combo is a drop-in upper receiver stabilizer and front takedown pin upgrade for the AR-15/M16/M4 platform. The kit pairs Cross Armory's oversized Pin Pal takedown pin with the Flop Stop upper receiver hold-open device, both machined from 4140 ordnance steel and finished in black melonite for wear and corrosion resistance.

The Pin Pal features an enlarged pin head that makes separating the upper and lower receiver faster and easier by hand. It includes the pin, a locking nut, and a MIL-SPEC captive bearing, and is fully removable so the rifle can be returned to factory configuration at any time. The matching Flop Stop addresses "Limp Barrel Syndrome" (L.B.S.) by holding the upper receiver in the open position, allowing quicker and more convenient reloads.

Marketed as state-compliant AR-15 parts, this Flop Stop + Pin Pal set fits standard AR-15-pattern rifles and carbines, including M4 and M16 variants, and installs without permanent modification to the host firearm.