I put a Timney Calvin Elite 1.5 lb in my R-15 and really like it. It comes with 4 different trigger “shoes” and I put the knurled post on mine. I really like that one the best. Was hoping it would help shrink my group size more but it contributed only a little in that department. Either way I like the crisp 1.5 lb pull VS the factory trigger which was OK but less than desirable.