Barrel twist rate for 20" 270.

If all your shooting are basic 140-150s, then the standard 1-10 is sufficient.
If you want a little more leeway to use the longer VLDs get a 1 in....8? I can't remember what twist rates McGowan and Shaw offer that are faster, or what other manufacturers offer fast twist .277 barrels.

Tucker25 said:

Hi, im looking at a custom barrel for a rem 700 build. Im going to get the barrel 20" long in 270 winchester. The question I have is what twist rate should i get. I will be shooting bullets 140-150gr.

Thanks,
Tucker

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Ablrs, tlrs, tgks and vlds will need a fast twist, partitions etc, standard 10 as @LoonWulf said. Personally if you're gonna milk that cartridge for everything it's worth get a fast twist, my sole regret on mine is that a fast twist isn't even an option.

Initially I was going to say unless you were going for a long range rifle with a 24 to 28” barrel I’d suggest the standard twist of 1-10” because it’s worked so well for bullets in the 130-150 weight range.

Then I realized the faster twist is more versatile so the bullets designed for 1000 yard shooting will stabilize along with the lighter weight projectiles. The slower 1-10” twist rate will not stabilize long-for-caliber VLD bullets and may not like those heavier than 150 grains either (Berger 170, Woodleigh 180, etc.). If you can get a 1-8” twist barrel, you’ll be set for almost anything you’ll be able to shoot from your .270.

Let us know what you decide on and how it turns out

Stay safe.

Unless you're going to shoot high BC bullets a 10 twist is fine. And there are only a handful of high BC bullets available in 270.

I'd still go with a 1-8 or so. You give up nothing, and gain the ability to shoot VLDs should you desire them at a later date.

Tucker25 said:

I should mention this is a hunting rifle so i will be shooting hunting bullets only.

Tucker

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Several high bc hunting bullets catching on in .277. Doesn't have to be target related.

horsey300 said:

Several high bc hunting bullets catching on in .277. Doesn't have to be target related.

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The 150ablrs didnt stabilize in two 1-10 .270s ive worked with. The 145 eldxs did tho.

Berger just came out with a .270 hunting bullet that runs 170 grains... it needs a 1-8”.
That would be some legitimate .270 elk/moose Medicine for sure.

https://bergerbullets.com/introducing-the-berger-270-caliber-170-grain-eol-elite-hunter/

Stay safe.

LoonWulf said:

I'd still go with a 1-8 or so. You give up nothing, and gain the ability to shoot VLDs should you desire them at a later date.

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+1
If you're at all interested in trying some of the heavier bullets in your .270, no reason not to go with a tighter twist. Some of the longer 150gr bullets (Interbonds and SSTs) have not given me the very good accuracy in otherwise accurate rifles, I think the twist was just a bit marginal. Add in the fact that with the 8.5 twist 27 Nosler and .277 Fury coming online, heavier .277 bullets are going to be more of a thing (Nosler already introduced a slick 165gr ABLR), I don't see any reason to limit yourself to a 10 twist on a custom barrel.

Speer made .277 170 grain component bullets for reloading quite a while back, they're just not today's high BC long ogive shape. I'd still consider them big medicine in a .270 Winchester especially from a shorter barreled rifle shooting to 300 yards or less.

https://www.gunauction.com/buy/17103501

But I'm not sure they would reliably stabilize in a 1:10 inches rifling twist rate barrel, I haven't run the calcs because I'm more highly enamored with the wide variety of. 284 projectile offerings.

As the others have mentioned what's the downside of choosing a faster rifling twist rate?

Mr. Zorg said:

As the others have mentioned what's the downside of choosing a faster rifling twist rate?

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In a semi-auto there is increased gas port pressure and increase in total bore pressure.

I don't see over stabilisation as a problem in my shooting, but over spinning a bullet can have a detrimental effect in terminal performance, causing premature failure.
I find a fast twist barrel gives a more dramatic hit on varmints than a standardly spun bullet, allowing the centrifugal forces to "explode" the bullet.

Poof!

For very long range an overspun bullet can resist changing the angle of flight and hit the target nose up, instead of nose on.
This can also affect the flight of the bullet, as it is now no longer aerodynamic and hitting the wind in one full side of the shank, sucking away the BC and even influencing accuracy.

Demi-human said:

In a semi-auto there is increased gas port pressure and increase in total bore pressure.

I don't see over stabilisation as a problem in my shooting, but over spinning a bullet can have a detrimental effect in terminal performance, causing premature failure.
I find a fast twist barrel gives a more dramatic hit on varmints than a standardly spun bullet, allowing the centrifugal forces to "explode" the bullet.

Poof!

For very long range an overspun bullet can resist changing the angle of flight and hit the target nose up, instead of nose on.
This can also affect the flight of the bullet, as it is now no longer aerodynamic and hitting the wind in one full side of the shank, sucking away the BC and even influencing accuracy.

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So in a 20" barreled .270 Winchester rifle, most likely bolt action as the OP mentioned Remington 700 action, and given the OP's list of options from 1:7 to 1:10 inches rifling twist rate, since that's the topic of discussion in this thread, I stand by my question.

If one chooses to look at the real picture vs taking a snippet of a post I made completely out of context that is. What constructive purpose that serves escapes me and I doubt I'm alone.

Tell us all about the long range shooting and varminting you've done with such a rig, especially one with semiautomatic action.

You asked smart guy...
Why don’t you tell us the cons for a bolt action?
I see two for a semi auto, and no others.
Or should we only let him know certain information?

LoonWulf said:

I'd still go with a 1-8 or so. You give up nothing, and gain the ability to shoot VLDs should you desire them at a later date.

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Truth.

Demi-human said:

Poof!

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I was watching a utube video of bullets doing that in flight, looked pretty cool.

Do you have a barrel maker in particular of interest? Some only make .277 in certain twists. For instance, a few such as Bartlein offer only 1:10.

Unless you are looking to fire only those super long Berger 170’s which necessitate a 1:8, I would look at either 1:8.5 or 1:9. I believe these two twists will give you the highest offerings of bullet weight accuracy. Brought on offers a 270 barrel in 1:8.5 that I’ve heard to be quite something special.

I agree with the above. If doing a custom barrel setup, there is no reason to stay with the normal 1:10 just because! Design the specs to what you want to shoot. If you are planning ONLY light bullets, go with the 1:10. more likely to shoot those long Bergers ONLY? Go 1:8. But if you are planning to experiment with several weights, and simply want the ability to shoot ANY ammunition to its fullest potential then go 1:9 or 1:8.5.

David Hoback said:

Do you have a barrel maker in particular of interest? Some only make .277 in certain twists. For instance, a few such as Bartlein offer only 1:10.

Unless you are looking to fire only those super long Berger 170’s which necessitate a 1:8, I would look at either 1:8.5 or 1:9. I believe these two twists will give you the highest offerings of bullet weight accuracy. Brought on offers a 270 barrel in 1:8.5 that I’ve heard to be quite something special.

I agree with the above. If doing a custom barrel setup, there is no reason to stay with the normal 1:10 just because! Design the specs to what you want to shoot. If you are planning ONLY light bullets, go with the 1:10. more likely to shoot those long Bergers ONLY? Go 1:8. But if you are planning to experiment with several weights, and simply want the ability to shoot ANY ammunition to its fullest potential then go 1:9 or 1:8.5.

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I honestly wouldn't be concerned about going with the 1:8, I don't really think there's much chance folks will be blowing up any normal hunting bullets in an 8 twist out of a 20" .270 win, and that's really the only realistic (if overblown) concern for a fast twist bolt gun. The 165gr ABLR requires a twist of at least 1:8.5, and the Nosler factory ammo is slinging them through that twist at 3,150 fps in the 27 Nosler.... Way tougher on the bullet than any .270 could be, and ABLRs are known to be a bit soft.

Kind of makes me want to put together a fast twist .270, with the newer heavier bullets and a better twist, it would really blow the 5 ksi lower MAP .280 Rem out of the water performance wise.

It’s not a concern of blowing up anything. Over spinning a bullet can be equally as much a cause of bad accuracy as too slow a twist.

Using a 1:8 they’ll shoot and hit the target sure. But the Accuracy choices will be more limited. That’s all.

Tucker25 said:

I have the option of 1 in 7,8,9,10, or 11

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Nosler - on their M48 Mountain carbon Rifle in 27 Nosler... used a 1-8.5".

...If that's any help.




GR

.270 was made for 130 grain bullets IMHO. I get sub-dime groups with my Classic Stainless Model 70 using Remington soft points. I'm typically not a fan of anything "Remington", but this Model 70 loves their ammo. It has a 1/10 twist. 1/9 would probably be better for 150 grain loads.

For a custom .270 I’d definitely go 1/8”.
However you are seriously handicapping the .270 with a 20”bbl. expect 150-200fps loss of velocity to a 24”bbl.
For a 20”bbl, I’d chamber for 7mm08. I get equal or better speed with similar or identical bullet weights from my 20” Rem Mod7 7mm08 as I do my 22” Rem M700 .270, or 24”bbl MkX Mauser.270. The 7-08 is a real “sleeper” of a cartridge. As a hunting cartridge, it beats the 6.5 compacts in every way.
My 7-08 easily gets 2,900fps with a 140gr bullet. Occasionally 3,000. 2,800fps with 150’s. The only category where the .260 or 6.5Creed better it is in reduced recoil.
The 7-08 does its thing with appropriately 9.0gr less powder than the .270.
Added; my Rem M7 has a 20”bbl. quoted velocities were from 20”bbl measured at ~15’.