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.
Bexar Arms - Anti-Walk Trigger/Hammer Pins
Rise Armament Blitz Elite Performance AR-15 Trigger w/ Anti-Walk
Gun Triggers Rifle Accessories
Trigger Upgrade Kit: Airborne Arms Geronimo 3.0 - 4.0 lb Trigger
AR-15 Trigger Options, Drop-In Triggers
MMC Combos AR 15 Trigger Upgrade Kit Including Davidson SKU: CO-82404
Trigger Upgrade Kit: Davidson Defense AR-15 3 lb Drop In Sierra
AR-15AR-10 ANTI WALK PINS - BURNT BRONZE, CERAKOTE, TRIGGER
KNS Precision AR-15/M16/AR10 Gen ST Non-Rotate Trigger/Hammer Pins
Trigger Upgrade Kit: Trigger + 308 LPK + Anti Walk Pins
KNS AR-15/ AR-10 Gen 2 Mod 2 Stainless Steel Barbell-Style Anti
AR15 anti-walk pin set for AR-15 lower receivers
Armaspec Anti-Walk Trigger / Hammer Pins Stainless .154 for ar-15
AR15/10 Anti-Walk Pin Sets