CCRN - Get what you want and quit worrying about barrel twist. 1/7 will shoot 55 gr. just fine; especially for anything you're likely to do with a carbine in the US. I have everything from 1/7 to 1/12 and ALL of them shoot 55 gr. just fine. 55 gr. is "blasting ammo" good for plinking/training at reduced ranges (IMNSHO < 150m = reduced ranges; especially when most "blasting" is done at <100m). It's primary value is affordability. If you want social ammo, use something else (and re-zero the weapon!). POA/POI shifts whenever you change bullets. FWIW all of my "plinkers" (carbines are plinkers
) are 1/9 for economic reasons, e.g. adequate quality, availability, and reasonable price. I'm currently using an RRA and a "frankengun" and they both run like sewing machines. TR and others have discussed the pitfalls of the various approaches (specifically the frankengun) and their advice should be heeded - caveat emptor. I can't justify the expense of an LMT right now, though I an jelous of TR's. RRA is a quality product for a reasonable price and they can be counted on to fix unfortunate "hiccups" (have to admit it's annoying when that happens and QA/CS are not up to expectations). I've owned several Colts over the years; I can't justify ever buying another one. My .02 - Peregrino