This low mass hammer is specially shaped and drilled for a 50% reduction in lock time. Compatible with JP Enterprises adjustable trigger. Hammer only, will not alter trigger pull. Fitting required.
Some Colt AR type rifles have been manufactured with hammer and trigger pins and holes which are approximately .176" in diameter. These are referrend to as "large pin" Colts. This was done to make it more difficult to put M16 fire control parts into an AR receiver. This is not found in all Colt models, just some.
All other AR type rifle manufacturers have stayed with the .156" diameter hammer and trigger pins and holes, or "small pin" which is the same spec used in all military M16 rifles.
Measure your pins or the holes in your lower receiver to determine if you have a "small" or "large" hole Colt AR