Twist rate certainly has an effect on accuracy, but don’t discount bullet quality as a major factor. There are a lot of poor to fair quality 55 gr bullets out there that can barely break 4 MOA in a stock run of the mill barrel, regardless of twist rate. Likewise, there are some 62 gr projectiles that share dubious reputations ( green tip and Armscor FMJ). I have shot plenty of MOA groups with Fiocchi Extrema 40 gr V-Max factory ammo out of stock S&W 1 in 8” twist and even PSA 1 in 7” twist barrels, and duplicated that with handloads with 40 and 50 gr Nosler Ballistic Tips and Hornady V-Max bullets. The old Federal American Eagle 50 gr Tipped Varmint factory ammo was also an eye opener for many AR-15 owners accustomed to cheap factory 55 gr FMJ ammo. Sadly, it has been discontinued by Federal, as it was too good to be sold so cheap. Bullet and barrel are primary determinants of accuracy, if either one is sub par, accuracy is more of an accident than a planned outcome.