260 AI barrel length for a light gun

[TX Badger]

I am doing a build and have a Savage short action and a Manners Elite Hunter carbon fiber stock on the way. I am about to order a 260 AI barrel.

Goals
-a light, accurate target, deer, and hog gun.
-shooting high bc bullets (140 gr.+)
-decent balance even when I attach my can
-targets to 1000 yds, animals inside 600 yds

Questions
-is there a point where the velocity gains slow relative to barrel length?
-is 23" reasonable?
-I'm in TX so I want a barrel contour that can handle some heat. How light can I go? I was thinking bull sporter-ish.
-Has anyone built a similar rifle?

 

[woodcr24]

FWIW, a 24" bbl standard .260 Rem can send a 140-grain projectile at a MV of ≥2,750 fps; in my neck of the woods, at 900' elevation, that projectile (ELD) remains supersonic until it passes ~1,500 yds (at 65F). I doubt that it would be much less with the shorter barrel that you are considering. Re: running the improved version of the cartridge, you might want to look into Quickload as a means of determining how efficiently your propellant will act behind the projectile. In other words, will going the AI route add much to the MV, or at least enough to justify the added price of reloading for it. Or to be more succinct: is 23" enough barrel to permit complete combustion of the propellant and give you the effective range that you are after? Again, QL will shed some light on this for you.

 

[TX Badger]

Wood,

I think you may have asked my question better than I did. I do not have QL and was hoping that someone had already done this leg work and may be able to share. I am not afraid of the AI forming process as that will get the break in done and the brass life is supposed to be so much better. Now if I'm not gaining enough speed to make it worth the process, extra powder burnt, and diminished barrel life I will either have to go longer or traditional 260.

Thanks for the response.

 

[woodcr24]

I don't have QL at present; it's on my list of "necessities" for purchase over the next month or so, so can't run the numbers for you at present. Loads that I have seen published online for the .260 Rem AI tend to reflect the use of a longer barrel than you are considering; generally, it seems that 26" is the shortest with data published. It's possible that there's a reason for this, meaning that either someone has determined that the gains are noticeable only in barrels that are ≥26", or that people running the AI cartridge in shorter barrels haven't been as vocal (or, I simply haven't found it).

Something to consider is that you might very well be using different projectiles for hunting and target shooting. Consider what your desired energy is at the POI and whether the projectile that you plan to use will deliver that energy at the range that you are looking to achieve, as well as whether or not the remaining velocity at that range permits adequate expansion. In the .264 category, the 120-grain TTSX is a very capable projectile for all of the game that you mentioned, but the optimal velocity for terminal performance seems to be >1,800 fps. You ought to be able to send that from a standard .260 at close to 3K fps from the 23" barrel. It might be enough for your requirements without the AI.

 

[Mikecr]

For a 'target' gun you need to think past velocity and consider muzzle pressures, which affect bullet release. Muzzle pressure could also affect the integrity& effectiveness of your 'can'(another counter variable to target shooting). High muzzle pressure conditions can lead to secondary peak pressures that go off the charts.
There are reasons all guns don't have ~22" barrels, and it isn't just velocity.

For target shooting, 260AI capacity, ~28" barrel. Not for velocity, but for consistent load performance and clean bullet release.
Don't let the trained monkey shooting with LR pistols or tactical assault guns send you down the wrong path. In accuracy, they're nowhere approaching a true LR rifle.

 

[TX Badger]

Thanks for the thoughts guys. I know there are no absolute right answers to these questions. I may just need to find a bunch of load data for the 260 and its AI cousin and see what I can extrapolate.

Wood,

I am getting the impression that 26" may be the standard for this round. That is what Terry Cross runs in his tac. set up in the article on 6mmbr. As for bullets, your point is valid, but do to time limitations, simplicity, and maybe a touch of laziness I just run the the heaviest bullet my guns like a call it good. 168 berger in my 7 rem mag, 115 berger in my 25-06... There may be better ways to skin a cat, but a 115 berger out of 25-06 does a good enough job for me

Mike,

When I say "target" I am thinking popping steel not tiny bench rest groups. Of course I want to make the gun I set up as accurate as possible, but there are always trade offs, right? This will be a gun to carry in the field as well. Am I correct in assuming that the muzzle pressure issues that you are referring to are more applicable to extreme accuracy for competition or am I misinterpreting?

Chris

 

[Mikecr]

The 260AI is a fantastic cartridge. Perfect capacity for best in 26cal bullets.
But it seems to me that you're set on butchering it's potential with tacti-cool maturities.

It's not what LR hunters or target shooters do.
Sniper's Hide

 

[TX Badger]

Easy there Mike, I think you are missing my point. Cool is not my concern and I am not opposed to a longer barrel within reason. But, in the deer blinds I hunt from, a 28" barrel (close to 30" with the suppressor adapter) is too cumbersome. I also do not want to have to go to a really light contour to keep the weight down on a gun that will be carried in the field. I am simply trying to gather info. If an acceptable length (for me) ends up butchering the cartridge's potential then I will move to a different chamber. I am not committed to any set up yet. And I have a big, long 7 rem mag for applications where a big long gun is applicable. The point of this build is to be lighter and more compact. In a few years this will be my sons gun.

 

[codyadams]

If you want heavy contour and light, get a carbon fiber barrel. More $, but it's what you want. I have a 260 AI with a 30" barrel, I like it because I can play with loads, and my most accurate load is actually 47.8 of 4831sc with a 140 which is under the hogden manual for a standard 260, but I'm getting 2960 fps still. My max load was 3020 with the 140, but accuracy wasn't as good. Berger 140 hybrid. And I also got 3025 max with 143 eld-X, but it was only 3/4 MOA. My current load is half moa. I want to play more with the eld-x, but I need to get more.

Also, with the AI you don't have to trim much, as it stretches very little, and brass life seems good. I love my 260 AI. Alot of people will say they wouldn't get a 260 AI, but most of those people don't have a 260 AI. Most people that do have one, love them.

 

[TX Badger]

Cody,

That sounds like a sweat rig. If a Proof carbon wrapped barrel was in my budget this would be a very easy problem to solve. Stiff, light, cools quickly. Unfortunately, I am tapped out on this build.

I am actually not looking to do an overly heavy contour. That was the other main question in my original post. How light can I reasonably go? Weight and length vs optimum performance..... Have you had a 260 AI in an conventional steel barrel, shorter barrel?

 

[codyadams]

Cody,

That sounds like a sweat rig. If a Proof carbon wrapped barrel was in my budget this would be a very easy problem to solve. Stiff, light, cools quickly. Unfortunately, I am tapped out on this build.

I am actually not looking to do an overly heavy contour. That was the other main question in my original post. How light can I reasonably go? Weight and length vs optimum performance..... Have you had a 260 AI in an conventional steel barrel, shorter barrel?

I have not, but even if your getting 6.5 creedmoore performance due to a short barrel, that is still exceptional performance. 2775 with a high bc 140 will still be a 1000 yard deer load, as far as performance with the correct bullet. Gunwerks uses about a 4 or 5 contour broughton barrel that is fluted and 25" long on their LR1000 guns, with obvious great performance. A 23" fluted barrel in a #4 contour would be light and work good, imo. That is about .670" @ 25", to give you an idea of the contour. Their guns have about a 2# stock, that barrel and a rem style action and weigh about 7.75 lbs unscoped if I remember correctly.

 

[nwkman]

I'm running a 20" magnum taper barrel in 260 AI with a 140gr Berger at 2750 fps @1500 ft elevation.

 

[TX Badger]

That's great to know for reference. I would think there would be a pretty significant fps jump from 20" up to 23" or so.

Thanks

 

[tbrice23]

Around 25 fps per inch. Usually.