i have a bushmaster 450 and love it. now i want to get a 223 upper to shoot varmints with. i am thinking about the stainless steel varminter 24" polished 416 stainless steel with 1x9 twist. they also sell 24" 4150 chromoly steel barrel with the same twist 1x9. or wlould the predator with the 20" 4150 chromoly steel barrel with 1x8 twist. what are the pros and cons of the barrels (stainless and chromoly) and twist rates? what are the pro and cons with the barrel lengths? iam looking for the most allaround set up.