i think i have an odd barrel. colerain .36 cal barrel on an underhammer i built. it shoots better the more fouled it gets. load. .350 swaged ball, .018 patch, 20 gr 3f. first 4 shots were round grp 2in in size at 25 yds. they got smaller from there. after 20 shots. last 5 went in a 1/2 in grp with 3 in same hole. any other guys run into this.