These AR15 anti walk / anti rotation hammer and trigger pins are what you need to keep your receiver from excessive wear and tear. Keeping the hammer and trigger pins from rotating is especially important when shooting full auto or with pistol caliber builds, such as 9mm AR15's.
Red Complete Anti-Rotation Trigger/Hammer Pin Set Style 15/.223/5.56 10/.308/7.62
Trigger & Hammer (Anti-Walk) Pin Set - AR15 or AR10/LR308 Black
AR-15AR-10 ANTI ROTATION TRIGGER/HAMMER PINS - SNIPER STEALTH GREY, TRIGGER /HAMMER PINS
AR Lower Parts - AR10 & AR15 Lower Parts
JMT Anti-Rotation Trigger and Hammer Pin Set
CMC Triggers Anti-Walk Pin Set AR-15, LR-308 Small Diameter
AR-15 Complete Anti-Rotation Trigger/Hammer Pin Set (Anodized Clear) » Guntec USA
AR-15 Complete Anti-Rotation Trigger/Hammer Pin Set (Anodized Black) » Guntec USA
Grip/LPK Combo: Skeletonized Polymer Grip + Recoil Technologies AR15 Ejection Port Door + Recoil Technologies Anti-Walk AR15 Receiver Pins