I have a DPMS 338 federal(.58" groups at 100yds) i get to keep. i am having to down size on number of guns due to divorce. thinking of going to a 243 cal upper to compliment the 338 fed. Is 243 critical for a barrel length? want something for pronhorns coyotes etc. ammo not $. easy to get. this would give me a broad range of hunting ability with one gun bag to carry.