Fast twist 270 Win

[GAHunterJim]

I'm looking to build another 270 Win, already have one in an ultralight package, this project will be on a Win 70 I already have in 30-06 and I want to use a Proof carbon barrel blank. The question I have is this...Proof only offers a 22" .277 barrel in 7.5 twist, pretty speedy for a 270 win. I want the 22" barrel as I will be using a suppressor. Bullet weights will be 140-150s but not sure if the 7.5 is going to cause me problems, would appreciate info from anyone who may have experience with such things.

You have ask why I'm bothering with a 270W? Well, I've built a few DIY pre-fits the last couple of years, all suppressed, and my Win 70s are collecting dust. I've got a 30-06 with a new Douglas barrel and McM stock that I can't figure what to do with it and won't sell it, if I'm going to use it, I want a new barrel/chambering threaded 5/8-24.

Just finished this one last week:

 

[Byrdman13]

If you are only going to shoot 140-150 grain bullets a 7.5 twist isn't really needed but should shoot fine. 7.5 twist would only limit you on velocity if you tried pushing a light cup and core bullet to high velocity. The bullet rpm tends to get a little high and the bullet starts to come apart from the rotation. I have a factory x bolt 7.5 twist 24" 270 and it shoots great. I've been pushing 165gr Nosler ablr to 2895fps and it works great. The heavy for caliber bullets is where the 7.5 twist shines.

 

[FEENIX]

I'm looking to build another 270 Win, already have one in an ultralight package, this project will be on a Win 70 I already have in 30-06 and I want to use a Proof carbon barrel blank. The question I have is this...Proof only offers a 22" .277 barrel in 7.5 twist, pretty speedy for a 270 win. I want the 22" barrel as I will be using a suppressor. Bullet weights will be 140-150s but not sure if the 7.5 is going to cause me problems, would appreciate info from anyone who may have experience with such things.

You have ask why I'm bothering with a 270W? Well, I've built a few DIY pre-fits the last couple of years, all suppressed, and my Win 70s are collecting dust. I've got a 30-06 with a new Douglas barrel and McM stock that I can't figure what to do with it and won't sell it, if I'm going to use it, I want a new barrel/chambering threaded 5/8-24.

Just finished this one last week:

My .270 AI has 1:8" (the fastest I can get in 2012) and is primarily built to propel the heavies, 165/175 Matrix VLDs. I also shoot 150 NABs without any issues.

My .257 WBY has a 1:7" barrel twist, which is primarily built to propel the 131 BJ, 133/135 Bergers, 134 Hornady ELD-M, 145 Black Hole, and now 163 Chinchaga. My .264 WM also has a 1:7" barrel twist for the 165 Berger. I asked Berger tech support if I would run into a problem using the lighter C&C bullets with my barrel twist, and they said no. A few LRH members use 115-120 C&C bullets in a .25 cal with a 1:7" twist without issues.

Good luck, and have a great time with your build.

 

[redneckbmxer24]

It will be fine, and no you're not going to push the bullet fast enough in a 270 to get separation, that's fuddlore. You have to be well over 300,000 RPM for a bullet to come apart and even then it really only affects the bullets with the absolute thinnest jackets.

At further distances than you'll probably be shooting a 270 with 140-150gr bullets you'll get a little more spin drift but that's the only thing you'd actually notice.

With the fast twist you always have the option of running heavies too.

 

[BEEMAN]

The faster twist will also give you the option to shoot some all copper bullets. The heavier options require much faster twist because of the length of these bullets.

 

[sable tireur]

The faster twist will also give you the option to shoot some all copper bullets. The heavier options require much faster twist because of the length of these bullets.

https://cuttingedgebullets.com/coll...ding&filter.p.m.customAttributes.caliber=.277

https://hammerbullets.com/product-tag/277-270/page/2/

https://badlandsprecision.com/product-category/bulldozer-2/

I've used all of these at one time or another. All harvest game well.

 

[Bucefal]

Going with a Proof carbon barrel for your 270 Win on the Win 70 sounds like a great choice. The 7.5 twist might seem quick, but it could actually pair nicely with the bullet weights you're aiming for.

 

[Byrdman13]

It will be fine, and no you're not going to push the bullet fast enough in a 270 to get separation, that's fuddlore. You have to be well over 300,000 RPM for a bullet to come apart and even then it really only affects the bullets with the absolute thinnest jackets.

At further distances than you'll probably be shooting a 270 with 140-150gr bullets you'll get a little more spin drift but that's the only thing you'd actually notice.

With the fast twist you always have the option of running heavies too.

It is possible to shoot fast enough in a 270. Not saying bullets will separate for sure at 300,001rpm but Hornady recommends keeping ther v max under 300,000. When calculated that is 3125fps with a 7.5 twist barrel. Easily possible with the 270 and 110gr or less bullets. But with non varmint bullets with heavier jackets and more weight like the 140-150 it's going to be tougher to get those velocities.

 

[Jpron]

I put one together for my dad a few years ago. I used carbon six with a 7.5 twist. You'll be fine with a 7.5. He was running the 175gr Sierra at 2940 with reloader 26. But now that 26 doesn't exist he switched down to Speer 150 gr. Those shoot very well also. His is a 26 inch barrel

 

[Leaf Litter]

Hornady doesn't make ELD-M bullets in .277 so you don't have to worry about bullets coming apart. I love shooting ELD-M's, but man are they flimsy.

I run berger 170 EOLs @ 3050 and 145 ELDXs @ 3175 out of my 7.5 twist 6.8 Western with no issues.

 

[sable tireur]

this project will be on a Win 70 I already have in 30-06 and I want to use a Proof carbon barrel blank. The question I have is this...Proof only offers a 22" .277 barrel in 7.5 twist,

The simple solution is to reset your desire for using only a Proof CF barrel. They are not the end all for rifle barrels. There are a dozen top quality barrel makers that can supply you with a slightly slower twist rate to work with the bullets you have chosen to use. This way you don't ever have to worry about thin jacketed bullet unraveling.

Then, if you absolutely HAVE to HAVE a Proof CF, be sure to discover the potential uses for solid bullets available for your testing. I listed several above.

Enjoy the process!