Range Report 284 Winchester - twist?

[michael_aos]

I'm about to order a 7mm barrel for a long-action 284 Winchester build.

Right now I'm expecting to shoot mostly the 180gr Berger VLD. I may experiment in the 162gr - 175gr range as well.

I'm pretty confident a 1:9" twist would be fine for all of these.

My question is if there's any other super-long high-BC bullets out there that might require a 1:8" twist? Or anything in the pipeline? Since I'm just getting started with this, I'd hate to go with a 1:9" twist now and then discover I should have gone with a 1:8" twist.

 

[kraigWY]

Re: 284 Winchester - twist?

Twist = s(L/c)Xc

s specific gravity (150 for a lead core jacked bullet)
L lenght of bullet
c cal

Example a 160 gr .284 bullet is 1.40

1.40/.28 = 5
150/5 = 30
30 X .28 = 8.4

I couldnt fine any 168 or 175 grn 7 mm bullets so I didnt messure them, but they would require a tad faster twist.

So I's say the 1 - 8 is what you are looking for.

 

[michael_aos]

Re: 284 Winchester - twist?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: kraigWY</div><div class="ubbcode-body">So I'd say the 1 - 8 is what you are looking for.
</div></div>

Berger's web-page recommends 1:9" twist minimum for the 180gr.

I've read some reports of other people having success with the 180gr and 1:9" twist. It may be a factor of muzzle-velocity.

I suspect I'd be OK with 1:9" for the typical, current 162gr - 180gr offerings. At least the ones I'm aware of.

JLK says 1:9.5" is optimal for their 168gr, and 1:9" for their 180gr.

I'd just hate to find out after I order the 1:9" twist there's some fancy gee-whiz-bang lathe-turned 175gr .800 BC 7mm bullet that requires a 1:8" twist.

Running the 284 Winchester in a long-action, I could accommodate REALLY long bullets.

 

[kraigWY]

Re: 284 Winchester - twist?

Lets look at this another way.

Throughout this site, and other gun sites you read post after poat about the fast twist in 223s being better, since a faster twist will shoot light bullets better the a slow twist will shot heavy bullets, (which is quite true).

So why is the 7 MM (.284) differant?????????

I would think, if in doubt, go to a faster twist.

JMHO

 

[michael_aos]

Re: 284 Winchester - twist?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: kraigWY</div><div class="ubbcode-body">I would think, if in doubt, go to a faster twist.</div></div>

Yeah, not disagreeing with you.

I have read though that a faster twist than necessary can over-stabilize a bullet. Exaggerate any irregularities in construction.

Faster twist means more friction. Potentially less velocity and potentially more fouling.

The 284 Winchester really shines when pushing the 180gr Berger @ ~2900fps.

I'd hate to give up 50 fps by going to a 1:8" twist if there aren't currently or aren't likely to be any alternatives that actually REQUIRE the 1:8" twist in the near future.

Any exotic alloy, or aluminum / polymer tipped, etc that are on the horizon?

 

[raptor99]

Re: 284 Winchester - twist?

1-9 is what most of the big dogs are using with the 180s in the 284s.

 

[Graham]

Re: 284 Winchester - twist?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Michael Aos</div><div class="ubbcode-body">I have read though that a faster twist than necessary can over-stabilize a bullet. Exaggerate any irregularities in construction. Faster twist means more friction. Potentially less velocity and potentially more fouling....I'd hate to give up 50 fps by going to a 1:8" twist...</div></div>First, you can't over-stabilize a bullet: a bullet is either stable or it isn't. Second, I know what you mean, but fast twist doesn't exaggerate irregularities, it theoretically causes groups to open up when bullets are not blanced or they yaw in the bore. If you shoot good bullets this shouldn't be an issue in a tactical rifle. Third, faster twist won't have a measurable effect on either pressures or velocities.

 

[michael_aos]

Re: 284 Winchester - twist?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: raptor99</div><div class="ubbcode-body">1-9 is what most of the big dogs are using with the 180s in the 284s. </div></div>

Yep, that's exactly my understanding as well.

 

[Graham]

Re: 284 Winchester - twist?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Michael Aos</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: raptor99</div><div class="ubbcode-body">1-9 is what most of the big dogs are using with the 180s in the 284s.</div></div>Yep, that's exactly my understanding as well.</div></div>Many shoot 9's. But some are shooting 10's. And some have fractional 8's.

For me the question is never whom, always why. Because whenever I've followed a big dog I've found myself blocked at the front by a big backside. I'll try not to point my backside at you, or to become one on your thread, but either you want to make your a decision based on an understanding of the problem or you want to imitate someone else. If you want to imitate, get an 8, 9, or 10. Either one will work just fine.

Here's a link to Bryan's article about bullet properties and barrel twist for 7mm Bergers:
http://www.appliedballisticsllc.com/index_files/7mmNumberOne.pdf

 

[300sniper]

Re: 284 Winchester - twist?

i have been shooting a 9 twist in my 284 with 175 smks and will order another 9 twist when this one is done. a 9 twist will work just fine for 180 vld's also.

 

[michael_aos]

Re: 284 Winchester - twist?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 300sniper</div><div class="ubbcode-body"> 9 twist will work just fine for 180 vld's </div></div>

Yeah, that's definitely my understanding. Lots of real-world examples where the 180gr VLD's work just fine with the 1:9" twist 284 Winchester (2800 - 2900 fps muzzle-velocity).

The question was really around whether there is currently or is likely to be in the near-future any high-BC 7mm bullets that require something faster than 1:9" twist 284 Winchester.

A 200gr bullet with a BC of .500 wouldn't be desirable, for example, so I don't really care about that.

 

[michael_aos]

Re: 284 Winchester - twist?

I noticed this box of Hornady 162gr AMAX has 1:8" twist printed on it.

 

[Wild_Bill]

Re: 284 Winchester - twist?

get a 9 twist i have run 3 284's for FG Class using 175gr Matchkings and 180gr bergers they work perfectly the A Max will shoot in a 10 twist 284 driven hard but the 9 twist will shoot any peojectile. I shoot back to 1200 yards in competition and no dramas.

8 twist barrels tend to wear quicker with higher pressures and place a lot more stress on the jacket, you cant overstabalise a well formed high quality match bullet but if their is a flaw in the projectile it is exadurated the faster it is spun.

 

[kyreloader]

Re: 284 Winchester - twist?

Spin drift would also be more in a 1:8 vs a 1:9 barrel, right?

 

[rmfield]

Re: 284 Winchester - twist?

Correct, but not much. Maybe an inch at 1000 yards with 180 VLDs.

Edit: I am just finishing a LA hunting rifle build for 180s using 1:9 twist, 24 inch #5 from PacNor.

 

[Jeffvn]

Re: 284 Winchester - twist?

Michael...the only bullet that may not fully stabilize out of your 9 twist .284 is the 190 Cauterucio. it is borderline in my 7WSM from 9 twist when its really cold outside, and unless you are going to run your .284 fater than my 7WSM (not too likely) I would consider an 8.5 for teh 190s. BE advised that Bob also makes the exact same bullet in 177 grains, which is GTG from the 9 twist.

My brother shoots a straight .284 Winchester out of a 9 twist Bartlaein and its a one hole hammer.

JEffVN

 

[michael_aos]

Re: 284 Winchester - twist?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Jeffvn</div><div class="ubbcode-body">the only bullet that may not fully stabilize out of your 9 twist .284 is the 190 Cauterucio</div></div>

Thank you. That's EXACTLY the kind of info I was looking for.

 

[Greg Langelius *]

Re: 284 Winchester - twist?

Thank you, guys; I was pondering the same question for the .280, which should work marginally better with the same bullets.

Greg

 

[Mark Walker]

Re: 284 Winchester - twist?

I have been running a 9 twist with 180 Bergers and have not had any issues. Very good combo, IMO.

 

[nutzo396]

Re: 284 Winchester - twist?

I counldn't make up my mind between 8 and 9 twist for my 280 build.Luckily Krieger had a 8.5 twist sitting on the shelf.I just dropped it off to Pierce this weekend. We'll see how she shoots shortly ( I hope ).

 

[Graham]

Re: 284 Winchester - twist?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Michael Aos</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Jeffvn</div><div class="ubbcode-body">the only bullet that may not fully stabilize out of your 9 twist .284 is the 190 Cauterucio</div></div>Thank you.That's EXACTLY the kind of info I was looking for.</div></div>You probably weren't looking for this info, then: My next barrel will start at 1 turn in 9.75 and finish at 1 turn in 8.9.

 

[michael_aos]

Re: 284 Winchester - twist?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Stiggy</div><div class="ubbcode-body">Krieger had a 8.5 twist sitting on the shelf</div></div>

I got in on the Rock Creek Barrels group-buy.

Ordered a 1:8.5" twist 7mm and 1:8.5" twist 6.5mm.

 

[josephberry]

Re: 284 Winchester - twist?

My .284 on a long action is a 9 twist. Shoots 180s fine, but I think the case is more suited to the 168vld.

 

[OilyOwl]

Re: 284 Winchester - twist?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Michael Aos</div><div class="ubbcode-body">I noticed this box of Hornady 162gr AMAX has 1:8" twist printed on it. </div></div>

I've a 22" Lilja 1-10" 7-08 that shoots the 162A-max wonderously.

My 284Win's have been 9",less regret.