Improving the 260...

[Gibbshooter43]

I am planning to Ackley Improve my Remington 260. I've read and considered all the arguments for and against the AI. My question here is what is the most ideal barrel length and twist to achieve the maximum accuracy and velocity. I realize there will be a process of selecting powders and bullets, and fine tuning them, but I really want to hear your tho'ts about length and twist.

 

[highdrum]

Are you going to build on a long action to take full advantage of that extra powder space? @ 2.85" oal the 260 case has heavy for cal 140+gr bullets sitting pretty deep in the powder space. I'd run a 24" bbl minimum if you're looking for max fps. 1:8 twist will be plenty, there are a few new bullets out that have great BC that require 1:7.5 but they're heavy and that small case would probably have better ballistics shooting a bit lighter bullets faster. Here is my stance on this......I sold my 6.5 creedmoor, and the 260ai is just a lil step above that case on a short action. To use extra powder space it needs be run on a long action, but then why stop there? If I were building a rifle to run on a long action that would have great brass, good barrel life, good performance, it'd be a 6.5x55 improved. Lapua brass, will run right with a 6.5x284 with less powder.

 

[highdrum]

Dbl post

 

[MudRunner2005]

26" 1:8 twist. I wouldn't go less than a Rem Sendero contour. I'd also choose a 5R-rifled blank if you don't already have one. Bartlein builds a nice blank.

Or, if this is for hunting, a 26" 1:8 twist Proof Research carbon fiber barrel might be a lighter options with good stiffness for LR accuracy.

 

[cjl2010]

20" 1:7.5 twist if it was mine. What's your goal for this rifle?

 

[Gibbshooter43]

It's to be a hunting rifle out to maybe 500yds and mostly for deer with the occasional song dog and maybe a cow elk during a predation hunt to 350yds. Other rifles will cover the varmits and bigger game. I just enjoy the challenge of loading something just a bit different, and that's born out with the 243, 250, and 25:06AI's.

 

[jimbires]

Gibbs , I've been playing with a straight 260 off and on for a couple years here's a link to that thread . I think most info is in the thread . Jim

https://forum.nosler.com/viewtopic.php?f=9&t=39051

 

[cjl2010]

It's to be a hunting rifle out to maybe 500yds and mostly for deer with the occasional song dog and maybe a cow elk during a predation hunt to 350yds. Other rifles will cover the varmits and bigger game. I just enjoy the challenge of loading something just a bit different, and that's born out with the 243, 250, and 25:06AI's.

I'll stick with my 20" barrel and 1:7.5 twist.

 

[J E Custom]

When I looked at the 6.5,s I chose the 260 rem AI for many reasons.
I had plenty of good 7/08 and 308 cases (Lapua) and felt it would be the best way for me.

I am a big fan of the Ackley,s and it seemed to be the right powder volume for a good 6.5 hunting round. With that said, I chose a 1 in 8 twist 3 grove barrel (For a little more velocity and longer throat life)
I also chose a 24" Sendero contour. the action I chose was a Remington 788 because of the center feed feature.

I did a traditional AI chamber using a 260 head space gauge so i could fire 260 ammo if need be. The rifle will stay just under 1/2 MOA while fire forming and in the fired cases 130 grain bullets will go beyond 3000 ft/sec and the 140, s are just under 3000 ft/sec. With the right load and barrel the AI will produce 100 to 150 ft/sec more velocity.

The 788 Magazine will take a COAL of 2.815 with space to clear, so I load 2.815 and seat bullets that will allow some freebore. case density is at 95 to 98% with the best powders so I don't worry about compressed loads with the 140 grain bullets.

In my opinion there are no downsides to the 260 AI and the fact that in a pinch you can use 260 Rem ammo that has equal or slightly better ballistics than the CM. and the fact that Lapua Now makes cases for it, I feel you are making a wise choice. Mine seems to realy like the 129 grain Accubond with the best 5 shot groups to date just under .200 thousandths and will realy send them fast and flat.

Just my opinion on twist and Barrel length.

J E CUSTOM

 

[FEENIX]

I'll stick with my 20" barrel and 1:7.5 twist.

That would be an excellent compromise, esp. when the OP is considering a suppressor (if legal in his state).

 

[Overkill338]

When I looked at the 6.5,s I chose the 260 rem AI for many reasons.
I had plenty of good 7/08 and 308 cases (Lapua) and felt it would be the best way for me.

I am a big fan of the Ackley,s and it seemed to be the right powder volume for a good 6.5 hunting round. With that said, I chose a 1 in 8 twist 3 grove barrel (For a little more velocity and longer throat life)
I also chose a 24" Sendero contour. the action I chose was a Remington 788 because of the center feed feature.

I did a traditional AI chamber using a 260 head space gauge so i could fire 260 ammo if need be. The rifle will stay just under 1/2 MOA while fire forming and in the fired cases 130 grain bullets will go beyond 3000 ft/sec and the 140, s are just under 3000 ft/sec. With the right load and barrel the AI will produce 100 to 150 ft/sec more velocity.

The 788 Magazine will take a COAL of 2.815 with space to clear, so I load 2.815 and seat bullets that will allow some freebore. case density is at 95 to 98% with the best powders so I don't worry about compressed loads with the 140 grain bullets.

In my opinion there are no downsides to the 260 AI and the fact that in a pinch you can use 260 Rem ammo that has equal or slightly better ballistics than the CM. and the fact that Lapua Now makes cases for it, I feel you are making a wise choice. Mine seems to realy like the 129 grain Accubond with the best 5 shot groups to date just under .200 thousandths and will realy send them fast and flat.

Just my opinion on twist and Barrel length.

J E CUSTOM

Your speeds sound like a .264 Win Mag, except using less powder. I loved my .264, but it seems it isn't too popular even these days.

 

[Gibbshooter43]

When I looked at the 6.5,s I chose the 260 rem AI for many reasons.
I had plenty of good 7/08 and 308 cases (Lapua) and felt it would be the best way for me.

I am a big fan of the Ackley,s and it seemed to be the right powder volume for a good 6.5 hunting round. With that said, I chose a 1 in 8 twist 3 grove barrel (For a little more velocity and longer throat life)
I also chose a 24" Sendero contour. the action I chose was a Remington 788 because of the center feed feature.

I did a traditional AI chamber using a 260 head space gauge so i could fire 260 ammo if need be. The rifle will stay just under 1/2 MOA while fire forming and in the fired cases 130 grain bullets will go beyond 3000 ft/sec and the 140, s are just under 3000 ft/sec. With the right load and barrel the AI will produce 100 to 150 ft/sec more velocity.

The 788 Magazine will take a COAL of 2.815 with space to clear, so I load 2.815 and seat bullets that will allow some freebore. case density is at 95 to 98% with the best powders so I don't worry about compressed loads with the 140 grain bullets.

In my opinion there are no downsides to the 260 AI and the fact that in a pinch you can use 260 Rem ammo that has equal or slightly better ballistics than the CM. and the fact that Lapua Now makes cases for it, I feel you are making a wise choice. Mine seems to realy like the 129 grain Accubond with the best 5 shot groups to date just under .200 thousandths and will realy send them fast and flat.

Just my opinion on twist and Barrel length.

J E CUSTOM

Thanks for your input. I usually find your responses well tho't out and well presented as long as you're not being attacked. And it really helps that I agree with your tho'ts regarding the 260AI. The general consensus favors the 8" twist, and the barrel length with one exception, is mostly 24". Again, thank you.

 

[FEENIX]

Your speeds sound like a .264 Win Mag, except using less powder. I loved my .264, but it seems it isn't too popular even these days.

My .264 WM is near completion. Built for that reason; not too popular ... and I am OK with it.

 

[Overkill338]

My .264 WM is near completion. Built for that reason; not too popular ... and I am OK with it.

I would let my son hunt with the .264, but he needs trigger time behind a rifle. Don't want him developing a flinch. The .264 has more bark than bite, but its bark can be severe.