Home Forums Hunting & Shooting Custom Rifles & Wildcats 280AI twist?

1/9...1/8.5....1/8?

Will probably be spending most of the time with 162's but I see the 175 eldx has a recommendation for 8.5.

Mines a 9 twist, if I built another it would be an 8 or 8.5.

I have a couple 7 Mashburns, one an 8-twist and one a 9-twist. I live and mostly shoot above 6000 ft elevation.

If you are going to shoot 160/162s exclusively any of the twists you mentioned would work. If you want to try heavies and you live at lower elevation and shoot when it’s cold I would get the 8-twist.

Mine is 8. Can't think of a reason I'd go slower on a hunting rifle.

8

Looks like it will be an 8. Thanks all.

I went with a 1-9" on my F-class rifle and it shoots 180 grain bergers great, I have not tried any heavier than that, I am at about 600 feet ASL so no gain from elevation. I just purchased a Brux 7mm blank for a hunting rifle 21-inch barrel and spec'ed a 1-8.5" to be on the safe side and I wanted to be able to shoot monos.

^^^^^This

What contour are you going with?

Mine is a 9 twist and handles 140-160 grain bullets great. I have not tried anything heavier so I'm not implying it won't. If I was considering a 170 grain and plus, I would go with a faster twist, as it would only help the cause.

I am shooting the 175g Nosler LRAB with 9T, 500 feet elevation with IMR 7828 and fed 210's, bug holes abound.

Wanting a KS (ish) contour. I see that Bartlein is willing to do that with a stainless so that's the most likely right now. Will try to talk to them Monday about a KS or slightly heavier with an 8 twist..

I think I'll be fine with anything 9 twist or faster. If something close in contour comes along with a 9 or faster twist I might jump on it.

I am at 9T with 162s and shoot 1 hole at 200 yards.

The motivation to go from 9T to 8T with the 175 ELD-x or longer bullets is to go from marginally stable to super-stable, and consequently maximize the bullet's BC, not to go from unstable to stable. Check your stability here and make sure the SG is at least 1.5 for the densest air you'll shoot in:

https://www.jbmballistics.com/cgi-bin/jbmstab-5.1.cgi

You lose about 3% of the BC value for every 0.1 drop in SG below 1.5.

I have a 1-10 and a 1-9, next one will be 1-8 so you should start there. 1-10 up to 160s, 1-9 up to 180s, 1-8 190s and above but better stability with the 175-180s.

Keep us posted on the rest of the build.

I'll try to remember to update. Plan is:

1/8 KS (maybe slightly larger) contour to 24". May end up at 22" but I plan on running it at 24" for a while. Could go with a 8.5 or 8.3, etc if something is in stock.
Defiance anTi long action with rail
Going to give a Manners EH6 a try to start with...hoping to like it, if not then maybe an AG composites or Bansner/HTS/LAW/whateveryouwannacallit. Can switch out an Edge with a 700 as a last resort. ADL or BDL depending on stock.
Likely a triggertech
Seekins or APA rings
Nightforce NXS 2.5-10x32 HV 600 with zero stopped elevation dial

I just picked up a Defiance action and am thinking a build in the ball park of yours. I think I’m doing the 280 AI but read the thread with the 6.5 06 AI build and it’s making me pause.

My Brux barreled 7RM is 8 twist. The 280 AI is pretty close to a 7RM and if I was building one, it'd be an 8.

DF

I had Melvin Forbes rebarrel a LH Forbes in 280 AI he said to go 1-9 so that's what I did hoping rifle shows up soon.

I checked to see what twist Kenny Jarrett uses in his pet .280AI, one of the rounds he pushes pretty hard.

His technical data is proprietary, not letting us mere mortals know his "secrets"...

Oh well...

DF

A buddy had one of Jarretts had a 1-10 280 Ackley and said it shot 140’s and 160’s fine. He had a couple on his site with 1-10 barrels. With today’s Bullets I’d never do that myself to a 7mm.

Funny thing about twist, I have lotsa faster twisted stuff and can’t find a negative. Same buddy broke down and built a 1-9 300 mag with a Brux and it wouldn’t shoot anything real well, he has a 1-11 300 Wby and it’s a drill with everything he’s used in it.

His is the first gun I’ve seen with a faster than normal twist not shoot normally accurate Bullets for beans.

The odd bum barrel gets churned out of shops, regardless of twist rate.

What do you mean Jordan?

Just that the barrel may be bad (or there could be some other mechanical problem) and the fact that it doesn't shoot may have nothing to do with the twist rate.

in 1999, I had a 7 STW built with a 1-11T, Pac Nor super match 3 groove. Used a zero freebore 7 STW reamer. 140g Nosler combined Tec bullet at 3750 shoots tiny groups, took 12 rounds to work up a load with IMR 7828 and 215's.

Twist the barrel according to the bullets you want to shoot, success will be easy to achieve.

I agree a 155%, the problem that stumps me is it is 3 - 300 Win Mags all with the same 1-9 Brux on them and all done by Kevin Weaver. All three have been shot with great bullets like the 180 TTSX, 200 AB, 200 LRX, 200 Partition with powders like H1000, RL26, etc in good cases, concentricity has been measured and is excellent. I’m not even talking a few rounds here and there, all three of them are mediocre with the 200 Terminal Ascent shooting very well in all 3. The same shooter can switch the 300 Win to a 300 Wby Legend and stack shots with all of the same bullets.

Oh, an it’s not the scopes as all three have had NF on top in Leupold BC rings and Warne bases.

A few has mentioned over stabilizing but to be honest I thought that was dead with today’s good bullets. I run 22 up thru 7mm with fast 1-7 to 1-8 barrels and they all shoot the lighter bullets well along with the long heavy ones.

It was half interesting to me that Jarrett uses a 12 on his 300 and a 10 on his 280. Apparently it works well for him since he wouldn’t be selling 8-10k rifles for what he does if they stunk.

Long rant, but it is just odd to me all of the other calibers have been awesome with fast twist with light or heavy while three of these 300’s made right after one another are dogs.

If you over twist a bullet, it is apt to shed it's jacket quicker.

Tune windows for light bullets for the super fast twist and caliber can be finicky, to say the least.

Twisting fast as you can per caliber for any and all bullets is like saying that riots cure the chrono virus. Of course, 3/4" is accurate to some guys where it is time to re barrel for others.

Makes sense Keith and I guess if I go under 3/4” with most bullets I don’t sweat it much. But not a one was a 3/4” gun with any combos consistently except one bullet.

Were the barrels made consecutively, as well? Also thinking about potential reamer or throating issues.

When talking about modern bullets, shedding jackets is really only a problem with the most fragile varmint bullets like the Horn SPSX. Bullet uniformity has become very, very good in the last decade or so, and over-twisting bullets is really not much of an issue anymore, except for when the absolute precision is required like in BR competition.

Twisting as fast as is necessary for the very longest bullets you intend to shoot is a good way to go for most situations except short-range BR types of applications.

It's strange, and unless all those other bullets had terrible uniformity the twist isn't the issue. Barrels that tend to be really finicky with the bullets and loads that they'll shoot usually end up being diagnosed as a bad barrel, IME.

As far as I know all three of the barrels were bought at the same time, the rifles were made one right after another as well.

Kevin sent a pic of the test load with 4350 and a 200 Berger that was one hole so everyone had high hopes for it shooting well.

My little brother has a gun that is just about done right now, 300 Win with a 1-8 Krieger coming pretty shortly. I also have a 1-8 Krieger sitting and waiting to get built into a 300 RUM. Makes me wonder if I made a mistake going with the quicker twist, but like I said, up till this point everything from all of the 224’s up through my 1-10 twist 375 all have shot excellent without being fussy.

I wouldn't worry about the twist, I think there's something else going on there. Can you replicate Kevin's results with the test load he gave you guys?

It would be interesting to have those barrels slugged, given that they were bought and likely made in the same batch.

I’d almost, might, believe it with something like a Partition since I have seen them not be as perfect from one box to the next on occasion but still good as a whole, but the TTSX, Accubonds and similar have always been great shooting bullets.

Bob used to rave about his 8 twisted 300 Win Mag and Partitions so it’s just an odd problem. 2 of the guns are back at Weavers right now getting new Benchmarks put on. Seems odd for Brux to put out 3 turds though. Usually don’t hear much of an issue.

Oh and all three are using standard 300 Win Mag SAAMI spec reamers. Brass and such are coming out straight and with the 3.6” Mag box really lets you stretch them out to work off the lands with most bullets. Seems like a great set up in principle. It’s just sucking in application.

where is the decision? You have to go on line to get a consensus on how ill informed you are? or you have to go on line to get a bunch of dumb [bleep] to tell you what to do ?

Hey keith,

I ended up going with 1/8.3 as it was available from a maker the smith likes. Hope you had a great 4th and were able to get your panties straightened out!

JCM

I built a Savage action and a Winchester action 280AI, both 9" twists shooting 140 gr.
I have a factory Kimber factory 280AI 9" twist that shoots 140 gr.

My
.280 Remington has a 1:10 twist rate. It will stabilize 160 grain bullets just fine. For 140s it's golden.

What manufacturer and contour did you decide on?