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Target /steel plate 600 yards and more if possible.What type of shooting do you plan on doing?
I have a 24” Krieger barrel and it will shoot 50 vmax decent at 3200 FPS but if I move up to 3400 FPS accuracy deteriorates. The rpm is just too high.A 1:7 with 50gr Vmax will do <1moa if it is a good barrel. Basically unless you want to shoot the 30-45gr varmit loads the 1:7 will do fine.
90gr SMK it is then ?
69/77gr. Guys shooting 90's in an AR are typically going 6.5
I think you can get a 90gr inside magazine length with 6x45, too.
Two identical barrels in 1-7 and 1-8 cost the same. A 1-7 will fling 55 gr ball ammo as well as a 1-8 can. No point to 1-8.The 1:7 shoots the 77 grain OTM rounds very well. If you’re just sending 55 grain 193 at cans then go 1:8 or 1:9. But the heavier bullets do very well with 1:7.
Edited to add: White Oak Armament makes great barrels. They don’t get as much talk in this type of circle but they are well worth the money.
Nope. Not in an AR-length magazine.I think you can get a 90gr inside magazine length with 6x45, too.
6.5 twist.... single loading and mostly high power guys
Nope. Not in an AR-length magazine.
Unless you custom throat and use 308-length magazines there is NFW that you can safely load a 90 grain bullet in a 223-length case to fit in an AR-length magazine.
1:7 would be my preferred choice for most stuff, especially as the heavier rounds get more popular.
It also shoots the military stuff just fine as well.
You may have an issue on the super light / fast varmint bullets however.
If your light weight varmint bullets hold together in the 7t, they make a spectacular mess out of rodents.![]()
I can get an 18" WHITE OAK ARMAMENT barrel pre chambered in 223 WYLDE for the right price , it comes with a 1:7 twist which seems a bit fast to me , I guess it will get heavy bullets spinning accurately? , what are your opinions ?
Thanks.
Nope.A 1-9" will stabilize anything you can push out of a magazine fed AR-15 in .223/5.56.
In retrospect, I see where you're coming from. For one, the tracer will mag feed. I can't think of any other bullets off the top of my head, but if they are longer than the general crop of 77 and 75 gr. OTM/HP, they would not stabilize.Nope.
It's pretty well documented that a 1:9 is marginal for 75/77gr bullets. Some people make it work with longer barrels and higher velocities but most with average length AR barrels have poor results.What will it not stabilize?
I’ve had success with them in as short as a 16” barrel. However, the only places I took them out to distance in a 16” barrel were high elevations.It's pretty well documented that a 1:9 is marginal for 75/77gr bullets. Some people make it work with longer barrels and higher velocities but most with average length AR barrels have poor results.
From the muzzle to transonic, I’ve generally found that altitude doesn’t have a whole lot of effect. Through, and beyond the transonic is where it gets marginal. The rotation as slowed enough so as to be unable to handle the disruption caused by going transonic.That's something that is rarely mentioned in articles or discussions on twist rates: altitude. I've never had an issue with 1-9 shooting 77 SMKs even with 16" barrels, but I rarely venture below 3k ft. If you are at sea level shooting a 14.5" barrel, then you might want a 1-7.
This group was shot at 300 yards in a light wind with 77 SMKs from a 1-9 twist:
Agreed. The only way to improve upon that is to get a shorter fatter cartridge. Then it’s a whole new ballgame.If you look up a bullet stability calculator like Berger's and start pluging in data you will discover that it's pretty much impossible to come up with a combo that will feed from the magazine and not be adequately stable in a 1-8 twist even at sea level. Unless you are shooting tracers or single loading 80-90 grain bullets, you gain nothing with a 1-7 over a 1-8.
True, you gain nothing. But you also lose nothing. So you buy the cheapest of the two.On the other hand, when you’re limited to mag feeding 77gr projectiles and under in a semi-auto, you gain nothing over a 1:8t.