Shot a friend's AR yesterday - he was clueless about twist rates, but I informed him last night

[3/4Flap]

As long as an AR shoots "Minute of Chest" at 100 yards or so is all that matters.

Not here.
My ranch rifle is simple homebrew PSA midlength upper/PSA lower, 1/8 twist bbl with a 4.5 lb LaRue MBT trigger and topped with an old Burris Fullfield 3-9 scope w/ German 4A reticle. I shoot varmints for coyote bait in the hundreds/thousands and while the shots are not usually over 100 meters a 3-4 MOA rifle won't cut it, tho MOA accuracy isn't needed, either.

Load is bulk Hornady 55 grain SP over 25 grains of 4895.

Groups below left to right give an idea of the level of accuracy it produces. All groups shot from same sitting position, elbows rested on knees as shown (we rarely shoot from the bench). The gun got smacked the other day and I rezeroed it.
50 meters/54 yard. 200 meters/219 yards final zero (4.5 inches center-to-center). 200 meters/219 yards (3.5 inches center-to-center).

I've an ArmaLite M15 National Match with a free-floated bbl that is a true MOA shooter but it's heavy. The PSA gets used constantly all year. Not as accurate, but definitely not inaccurate, either.

 

[Golddollar]

With all this talk about twists I'm looking for Chubby Checker to join the Forum.

 

[walkin' trails]

I have a 1-9 gun that was supposed to be good for a minute and a half at 100 yards. With Hornady V-Max 55 grain, it's capable of sub MOA. Popular opinion said the 1-9 was best compromise for 55 and 62 grain fodder. It think it's more of how a particular barrel likes a particular bullet than twist in many cases - at least for the hose of us who know just about enough to dangerous. I've got a 1-7 also that is a 1.5 MOA with 62 grain. My 1-9 was used for work with 62 grain SPs and never seemed to shoot as tight as advertised. Only after a scope and some instruction did it exceed its purported potential, and not with the prescribed duty ammo.

 

[Dan W. Cady]

My 1:8 AR with an 18 barrel is capable of sub 1 inch groups at 100 yards with surplus SS109 62 grain ammo. Matching the right bullet weight to the barrel twist rate makes a huge difference with accuracy. My brother has a Remington 700 in 5.56 with a 1:12 twist, if he shoots anything heavier than 45 grain ammo the bullets keyhole at 100 yards. When using 45 grain varmint ammo you can put 5 rds through one ragged hole at 100 yards.

Thats interesting as the standard twist in the original SP-1 AR was 1in12. Standard twist in 222, 222Mag and 22-250 1in14. I have never had any stability issues with 55-60Gr bullets.

 

[cowboy94916]

I was with a friend in South Dakota, reducing the priare dog population, when he looked over to me and says, I think my barrel just puked. What makes you think so? I replied. His reply was, well all of a sudden I can't hit anything. I spotted for him on a dog when he fired dust flew yards from where he was aiming. So I set up a target about 50 yards out and had him fire a shot. Classic miss. Dust flew in front of the target on the edge of a PD hole, Second shot was classic keyhole. Well I went forward to retrieve target and I see a bullet in the dirt, bringing it back i comment that someone is shooting some very expensive Barnes copper bullets in the dog town.
Well my buddy looked at me, his face turned red, and an expletive came out of his mouth. Turns out when he packed for the trip he grabbed a ammo box full of his 70+ grain match loads built for his 1 in 8 twist 223 and he was shooting his 1 in 14 twist remington varmint. A quick trip back to the truck retrieving the correct ammo and low and behold he waas making nice hits well out past 300 yards.
He had been so bummed, that at one point I coulda bought that rig off him for a $100 bucks.
Lesson learned mark your ammo cans for the rifle they are built for.

 

[shocker]

PSA 18" stainless barrel, 55 grain Federal FMJs, 27 grains BLC-2, mediocre scope, will group 1 1/2" at 100 yds. If I had a choice I would have preferred a slower twist than 1:7, thinking I'd gain a little velocity and throat erosion would less. Maybe.