I just sold my mini tatical, it was fire everytime reliable. That said,I spent a lot of time at the range with it firing fmj Winchesters, Tulo russian stuff, reloads with different bullets and powders and always got the same results. Off the bench the first group would be the best, as small as sub moa with a 55gr handload or as large a 3 moa with other ammo. The next groups would be larger and poi would start to wander. After 3 or 4 strings the groups would look more like a pattern than a group and poi was anyone's guess.
I owned a bicentennial model and sold it after less scientific accuracy testing in the late seventies. Information only.