I bought a tc encore 204 one year ago at cabellas they mounted alaskan 6x scope, sighted in it shot good groups, but the next time out zero was off by one or two inches side to side and up and down, tried all the mount and remount on the scope, finally replaced scope with a leoupold vx111,seemed to hold zero went back out today shot 1 1/2 left 2 high, does any one know what the problem is? thanks Rob