1:7 twist is for longer bullets 75 gr. & up My target AR-15 has 1:8, but for an all round AR-15 are 1:9 i think can shoot up to 69 gr. accurate, older 223 bolt guns & early mini-14 were 1:12 you would have to shoot 40 to 55 gr. to get best accuracyWhats the difference between a 1:7 twish and say a 1:9 twist? Is one better for longer range? Will one cause the bullet to tumble sooner, or if it hits something? Still trying to get some info before i purchase my AR
1:7 twist is for longer bullets 75 gr. & up
I'm talking about what weight should be the most accurate for the twist?????????
While 1:7 does very well with those heavier bullets, it also does well with 55 and 62 grain. That's why 1:7 is so popular, not to mention the Mil-spec choice. Not trying open a can of worms(not even saying 1:7 is my favorite), but don't mislead the OP into thinking that 1:7 is only for 75gr bullets.
My AR has a 1:9 twist, which allows me to shoot 55gr accurately for plinking or shoot 62 or 69 grain match bullets for target shooting. I would recommend 1:9 for an AR, unless its sole duty will be as a match rifle in which case you would want a faster twist rate like 1:7 to stabilize the long heavy ultra match rounds.
As an example my bone stock 1:9 twist, 4140 chromemoly, non-chrome lined 16" barrel can shoot 1 moa (1" groups @ 100yds) with basic PMC Bronze ammo and 1.5 moa (1.5" groups @ 100yds) with steel surplus ammo. Thats plenty enough accuracy for plinking or varmint hunting at short ranges.
So I would want a faster twist for a heavier bullet. How much difference would your group be with the same bullets in a 1:7 twist instead of 1:9? I couldnt imagine it'd be too much different, just trying to get a perspective on this.
So I would want a faster twist for a heavier bullet.
I seen above its mentioned mil spec is (typically?) a 1:7 twist, so i looked up .223 vs the 5.56 nato, and the average .223 bullet has 55 grain, while the 5.56 has 75 grain. So since mil spec is 1:7 i'd assume thats because the military uses the "heavier" 5.56 rounds as opposed to the .223.
According to what I am reading from you guys that should work best.
Assuming that you understand why you will get better results, is the 'wwb vs match ammo' difference, and not the 55gr vs 65gr difference.