atr

I am extremely new to tactical shooting so excuse my probably very ignorant question but I don't know where else to look. I am wondering if there is any 20 moa base that will fit on a mossberg atr 100? Yes I know that putting a 20 moa base on a mossberg atr 100 seems somewhat pointless as it's...

ok i got a friend who is looking at this mossberg ATR. he wants it in a .243 for coyotes and deer. Problem is he hunts in an area that could offer some long shots on deer 400yds plus. the twist rate on the .243 is a 1 and 10 and it has a 22 in barrel. I think this is an inadequate cartridge...