i just put a cbi 223 barrel 26" varmint contour (wylbe chamber)on as well took my chamber readings with 75gr. match and amax's as well as 80 gr. amax i will have no problem seating 80 gr heads out some yesterday during break in i shot some junk bullets (75 gr.) thru it shot well most groups @ 100 yds were 3/4-1/2 with no load developement . i'm going to load up some of the same heads as well as 80gr amax heads and see what they will do @ 300yds(range i prefer to shoot at) hopefully next weekend i'll let you know how it does.