gaseousclay
New member
Can any of you weigh in on the effectiveness of 5.56 77gr ammo over say 5.56 55gr ammo? Also, does twist rate matter between these two cartridges? My S&W M&P sport II has a 1:9 twist rate, but I read a couple of articles that suggested 5.56 77gr is best used in a barrel with a 1:7 or 1:8 twist rate. I’m assuming the barrel twist rate will effect accuracy the heavier the load of the cartridge? Or does it not matter?