What barrel twist for copper?

[deckhandmike]

Alright, let me try this again. Calguns was being wonky with double posts.

So for copper specifically what twist should I look at for my new .308. I know you want faster for lighter bullets but the copper is longer. Does any of that actually matter? Rifle will be a Remington 700 with a proof carbon barrel.

[deckhandmike]

I will be using 130 grain and 150 ttsx ammo.

[sacrvrrat]

Most would recommend 1:10. You could probably could get away with a 1:12. I would just get a 1:8. Copper doesn?t mind being spun fast. Gives you more options.


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[200Apples]

Here we go again lol

If "copper doesn't mind being spun fast", that would be because it, as a homogeneous material, will be better balanced along it's axis.

Just another reason why folks who use and like pure copper projectiles really like 'em.


/cap'n obvious

[BOBGBA]

Barnes load data for the .308 uses a 1:12 twist.

https://www.barnesbullets.com/wp-content/uploads/2021/05/308WinchesterForWeb.pdf

https://www.barnesbullets.com/load-data/

[Dirtlaw]

Interesting thread. I would think if the weight was the same ... but then again maybe something else is in play.

[deckhandmike]

Interesting thread. I would think if the weight was the same ... but then again maybe something else is in play.

Yeah, I’m sure some smarter people have figured this out. Just curious because this will be a copper only gun. Figured I’d ask first.

[200Apples]

Like Mike was saying in the OP, copper is a longer bullet since it's less dense than lead. Longer bullets usually require a bit more enthusiasm in the spin...

And if it's any consolation I have in stock those same Barnes' in the same weights for my 17.1" Ruger Scout. I can't recall it's twist rate offhand but it's in the neighborhood of 1-in-10".

[Dirtlaw]

Like Mike was saying in the OP, copper is a longer bullet since it's less dense than lead. Longer bullets usually require a bit more enthusiasm in the spin...

200 ... Doggone. I wish I was as smart as you are. What you say makes sense.

[200Apples]

You're smarter, trust me.

I only know what calguns, TheHighRoad and the Marlin forum have shown me over the years. That, and actually handloading and shooting my own stuff.

[NaClAddict]

My tikka 270 is 1:10 and spits copper just fine. Not sure if it’s optimal but definitely good enough for less than 1” at 100 yds.

[Calif Hunter]

Like Mike was saying in the OP, copper is a longer bullet since it's less dense than lead. Longer bullets usually require a bit more enthusiasm in the spin...

And if it's any consolation I have in stock those same Barnes' in the same weights for my 17.1" Ruger Scout. I can't recall it's twist rate offhand but it's in the neighborhood of 1-in-10".

Chris is right - the length of the bullet is what dictates twist rate. Longer bullets need a faster twist. If you are sticking to the lighter weight .308 bullets, a 1 in 10" twist is fine. I would go 1 in 8", though, just in case I wanted to use some really long high BC bullets at some point down the road.

[Kevin11mee]

Copper projectiles usually require a faster twist because they are longer. Barnes recommends a 1:11 twist or faster for their 175-180 grain bullet, and a 1:10 twist for their 200 grain bullet, so you are probably good with a 1:10. A 1:8 twist is probably faster than necessary for the 308.

[JackEllis]

Have a look at this: https://bergerbullets.com/twist-rate...lator-updated/

[stonefly-2]

You want faster for "heavier" but that was just something in the water from when all we shot was lead.

It was never the weight, it was the length.

(or more correctly the length of the bearing surface of the bullet)

We just didn't recognize that for there being nothing to compare between.

Why have you decided on 130 and 150 gr.?

If that's "in the water" from that being what you liked in lead loadings the answer you seek might best be started with a comparison of the bearing surface of the loads you liked before and that of offerings in copper.

If it's for some other reason you're going to want to go with the fast end of the rifling choices because of the crazy long bullets you chose.

Personally after my little voyage of discovery in loading copper for the Swede I would go with the 110 gr. .308 if I were you and worry more about getting the c.o.l. right.

That gives you more wiggle room pressure wise for the speed you're going to want with copper anyhoo.