Chrome lined 1/2x28. It shoots like a dream anything from 52grs up to 77grs. I don't get to punch paper as much as id like so i cant say what it prefers but i've taken a liking to 75 hpbt over imr 4064 around 2875fps. That really seems to fight the wind up here and coyotes dont like it. The stock is nice but i think i may swap out a magpul prs for looks.Chrome lined or nitride? Hows it shooting for ya & what loads does it like? The RPR stock is bitchin man, nice setup. Also, 1/2x28 threads?