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1:7 Twist , whats it good for ?
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The only reason to not get 1:7 is if you're shooting varmint bullets.
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.
It also shoots the military stuff just fine as well.
You may have an issue on the super light / fast varmint bullets however.
1:7 would be best with 65gr or heavier bullets but will still work with 55gr. 1:8 seems to be the universal twist that works with all.
If mag feeding from a ar get a 1-8 twist. If single hand feeding the 1-7 might be the way to go. A 1-7 twist is marginal with a 50 v Max but a 55 vmax works quite well.
First 3 shots of Magtech OTM 77 SMK out of a 16” 1:7 WOA. I personally prefer 1:7. It shot cheap PMC bronze 55 grain FMJ right around 1” as well. My previous 1:7’s has done very well with 60 grain V-Max’s as well.
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.
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.
No real reason to go with anything other than an 8 or 7 twist in a 223 semi, and I'd take a 7 over an 8 every time.
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.
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.
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.
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.
Yeah, I totally misread what you were saying, hah. I thought you were referring to 6.5mm cartridges, not 6.5 twist. Whoops.
I was talking about 6x45mm, not 223. If you go to a big enough bore, you can absolutely get heavier than 90 into an AR mag, just a matter of how fat you want to go. There's several 6mm projectiles in the 87-90gr weight range that are shorter OAL than a 77gr .224 TMK, but I can't remember how many of them really get jammed too deep in the case. if you don't care about them being too deep, there's been 100+gr subsonic .223 loads developed, too, that still fit in an AR mag - but effective range was extremely short with them.
That's a high quality barrel at a fine twist rate for what you want to do. Buy it with no regrets. Woa is gtg.
If your light weight varmint bullets hold together in the 7t, they make a spectacular mess out of rodents.
PM Sent. Got a 20" 1:7 Kreiger sitting around if your looking for a top tier cut rifled barrel at a killer price with matching headspaced bolt
Just got a new Rem 700 .223 from a custom builder.
Different animal from AR.
Read some shit about 1:7.7 being the jack of all trades twist so I had Bartlein make me one up.
I primarily shoot 77s but would like the ability to be poor on occasion.
Time will tell if I got the master of none....
Different animal from AR.
Read some shit about 1:7.7 being the jack of all trades twist so I had Bartlein make me one up.
I primarily shoot 77s but would like the ability to be poor on occasion.
Time will tell if I got the master of none....
If your light weight varmint bullets hold together in the 7t, they make a spectacular mess out of rodents.
I once shot some light plastic type training rounds through my 1:7 AR
At 25 yards they were going to make a mess if they hit something as they were tumbling end over end by the time they hit the paper HA!
Kind of like when I tried the Lapua Subsonic .308 rounds out of my 1:12 AW rifle... at 100 yards you didn't want to get hit by that bullet, it was spinning end over end.
I'm not sure if that counts for extra kill points at very close range or not HA!
I have a 20" WOA Varmint upper with 1:7 twist. I briefly tinkered with Hornady 75 OTM, 75 & 80 Amax, 77 SMK & TMK, and 80 SMK. It seems to like Sierra the best, but everything I've loaded shoots pretty dang well. I settled on 77 TMK's for my magazine fed ammo, and 80 SMK's for my single feed ammo. I've never used this upper for light bullets, but I do have a 1:7 Colt and it shoots 55 FMJ just fine. At the extreme lightweight/high velocity end of things you might spin apart bullets, but I'm not certain you'll easily reach that condition with an 18" barrel.
My opinion?
Buy it and shoot bullets. 55gr+ will do well, some better than others.
I have a 16" mid length 1:8 because, well.... Because I felt like it. Torso-sized steel is scared of me out to 500 with my "fodder/plinking" 62gr loads (mixed brass, 26.5 gr BL-C(2). 2830 fps, SD 20, ES 90. 2 MOA all day long.
Your 1:7 should be able to do even better with 62gr and heavier.
First, ya gotta understand why the 1-7" twist came about. With the then new M16A2 (1985), the military wanted a heavier bullet that would remain stable farther out than the current M193 (55 gr. FMJ). They settled on the 62 gr. bullet (M855). This bullet only required a 1-10" twist, but the idea was to tighten the twist up in case someone came along with a better or different bullet in the near future. Once the process had moved forward, the government agency overseeing the cartridge mandated it have a matching tracer round. Due to the added distance a M855 would travel over the M193, the tracer bullet had to be long. So long in fact, it took a 1-7" twist to stabilize it.
That is where the 1-7" twist came from. Just to stabilize that tracer
A 1-9" will stabilize anything you can push out of a magazine fed AR-15 in .223/5.56. However, if you want to single feed longer bullets you can make use of the 1-7" twist. Or, shoot tracers, you'll need that 1-7" twist. You will not be able to load anything 80 gr. or even some 75's (Hor A-Max) to mag length. NEVER, when reloading, seat the ogive below the neck!
Fast forward to today's quality capability. In 1985 bullets didn't have the concentric quality that today's bullets have. We're talking copper jacket to lead core. With too tight of a twist, it tends to exagerate the distance a bullet goes off if the harmonic balance of a bullet is off. Meaning, accuracy suffers with a tight twist shooting non-concentric bullets. This is why benchresters shoot the slowest twist they can. It's an old truism that is not as true today as it was thirty years ago. Concentric bullets of today (1/10th the tolerances from 1985) are not nearly as prone to lose accuracy if overtwisted.
The problem with light varmint bullets with light jackets is they come apart much easier if spun too fast. Load them up to a speed they don't come apart and have a blast with them on varmints. But, if you start not seeing any impact, or that dreaded grey cloud 50 yds. out of your barrel, you need to slow them down.
If you want to shoot heavy bullets that need a 1-7" twist from a magazine, get a Valkyrie.
That is where the 1-7" twist came from. Just to stabilize that tracer
A 1-9" will stabilize anything you can push out of a magazine fed AR-15 in .223/5.56. However, if you want to single feed longer bullets you can make use of the 1-7" twist. Or, shoot tracers, you'll need that 1-7" twist. You will not be able to load anything 80 gr. or even some 75's (Hor A-Max) to mag length. NEVER, when reloading, seat the ogive below the neck!
Fast forward to today's quality capability. In 1985 bullets didn't have the concentric quality that today's bullets have. We're talking copper jacket to lead core. With too tight of a twist, it tends to exagerate the distance a bullet goes off if the harmonic balance of a bullet is off. Meaning, accuracy suffers with a tight twist shooting non-concentric bullets. This is why benchresters shoot the slowest twist they can. It's an old truism that is not as true today as it was thirty years ago. Concentric bullets of today (1/10th the tolerances from 1985) are not nearly as prone to lose accuracy if overtwisted.
The problem with light varmint bullets with light jackets is they come apart much easier if spun too fast. Load them up to a speed they don't come apart and have a blast with them on varmints. But, if you start not seeing any impact, or that dreaded grey cloud 50 yds. out of your barrel, you need to slow them down.
If you want to shoot heavy bullets that need a 1-7" twist from a magazine, get a Valkyrie.
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.
So yeah, I stand corrected, one would have to go to specific bullets rather than the general statement I made.
I would also have to say from shorter barreled AR's, transonic stability may not always be possible as speeds do not induce enough rotation to keep those bullets stable through the transonic range.
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It's an excellent to match twist to weights but then I heard anecdotal stories about 1x7's that shoot 50-55 grain bullets better than 75-77 grainers. I would put more faith in the manufacturer of the barrel rather than the actual twist.
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.
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.
In any case I hope my original post would show the OP he won’t go wrong getting a 1-7” twist.
Added: loads were full power Mk 262 clone. 25.5 gr. of RE-15. That may be an old load but it’s what I understood it to be. Chronoed at 2690 FPS.
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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:
This group was shot at 300 yards in a light wind with 77 SMKs from a 1-9 twist:
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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.
The caveat there is “just how marginal” can you get away with. Example being a 1-14” twist pushing a 60 gr. flat base vs a boat tail. The former will stabilize, the latter won’t. That’s at 4K ASL. Move down to sea level and any instability could make a marginally stable bullet go radically unstable.
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.
Agreed. The only way to improve upon that is to get a shorter fatter cartridge. Then it’s a whole new ballgame.
The 90 grain SMK was made to try to make National Match A2's into 1000 yard guns. AMU did some work on it but it still ended up as a .223 in the wind, better than 80's bit that doesn't say much.
I haven't tried RL15 in mine but 24-24.5 of Varget is good, 2700-2750 fps in a 20 inch barrel. I've loaded 52 grain SMK to 82 grain Bergers. I shoot H335 for the light bullets 52-55 and Varget for the 77's and up. I have, but have not worked up 8208. Which from all accounts is a great powder.
I haven't tried RL15 in mine but 24-24.5 of Varget is good, 2700-2750 fps in a 20 inch barrel. I've loaded 52 grain SMK to 82 grain Bergers. I shoot H335 for the light bullets 52-55 and Varget for the 77's and up. I have, but have not worked up 8208. Which from all accounts is a great powder.
Really comes down to application.
In a bolt gun or a single fed AR (if that’s even a thing?), shooting heavier bullets longer distances, I could see the draw to a 1:7t. Even for precision style ARs shooting distance I could see using them for additional stability through transonic.
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.
In a bolt gun or a single fed AR (if that’s even a thing?), shooting heavier bullets longer distances, I could see the draw to a 1:7t. Even for precision style ARs shooting distance I could see using them for additional stability through transonic.
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.
True, you gain nothing. But you also lose nothing. So you buy the cheapest of the two.
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