A few of us long range F Calss shooter are debating on the merits of the two, standard 260 or 260AI. Barrel length is not an issue, we can run them long. Which would be the best choice for up to 1000 yards?

Repeater? COAL constraints?

For belly bench,it'd be 6.5-284 for me...if forced to slum a .264"...............

One of the crew has a 6.5x284, but barrel life is short, and he can't get his to shoot ( at least to his satisfaction) good enough.

The chambering is mechanically proven,in it's innate abilities to work wonders. If the 260 weren't enough to make me giddy,I'd certainly drive the 284 hull instead...................

A 260 AI pushing a 123 Scenar at 3,100 would put the giddy into it.

24.0 MOA and 1,550 at 1,000 yds.

How much slower do you figure the 6.5-284 to be?................(grin)

260 AI for me......nearly same performance as the 284 case but

less powder...two weeks ago I let a buddy shoot mine...an 18#

Savage/Pac-Nor set up....dialed it in for him and he slammed

the 10" steel plate at 1K yds 5 outta 5....Berger 140s or

Sierra 142s do the same thing...RE19 is my fuel....

Do it whenever I want with a 21" 223AI/75A-Max combo...............

How much velocity could you get with the standard 260 and 30" barrel with 123's and 140's?

Never drove a 30" and hope to never lose a bet of that size...............

Not even close.

Pressure for pressure, I'll always get 200 fps faster in a 284 case.

I've got a 30" and 32".

In the 30" i was moderately pushing Cauterucio's 120gr. 3100fps. I sold that gun and just recently got it back.

I put a 32" Mcgowen on another action and am comfortably pushing the 123 sierra's 3300fps. I am going to switch to the 123gr. Lapuas. Better BC.

This is with a straight 260.

260Shooter, It doesn't look like an Improved is needed. is it? What action are you using? Thanks, Luke

I thought long and hard about an AI. The fireforming and only about 100fps gain wasn't worth it to me.
Terry Cross shot an AI but since switched back to straight 260.

My 30" is on a Remmy short action turned into a single shot.
My 32" is on a savage 110 single shot.

I've had good luck with powders like RL-17,N-560,N-160, RL-22.
Seems like i can get the speed and not pushing it as hard like i had to with H-4350

Good info, Thanks, Luke

2995 with a moly 140 Berger & RE19...
fast enough for me in a 308 case........Pac Nor 8 twist/3 groove/27"

fire forming is a pain in the arese simply put! if your going to gain 200 fps or more OK. I just settle in with my 25/06 and bare the results, which aren't just to bad. However mine is for strictly hunting and not long range targets.

I would start with a .270-WSM case necked down to a 6.5 and go ride em cowboys!!! This ought to push a 140 grn bullet plenty fast enough out the end of a 26 inch barrel.

6.5x300WSM....its out there

WSM is fast for a 6.5, as is barrel life, some say 800 rounds..

What's the % gain in capacity?? I can't believe that, pressures being equal, a 200 fps is possible.

Luke asked about a comparison of a 260 to a 260 AI. 9 out of the 20 post so far have gone off on their favorite but some other caliber. Interesting.

I am interested in experience with the 260 compared to the 260 AI as well ... but I am not interested in the 6.5 x 284 or other calibers. The 260 or 260 AI is all the gun I need for hunting in the east. If I were out west I would be open to other calibers. I have also wondered about the extra effort to fire form the AI as well as other plus and minus aspects of the AI. I currently have a 260 and am considering a 260 AI for my grand son. Some times wonder if I should keep it simple and stick with the 260.

I am 6.5 fanatic, so I may be biased. I have several 260's and 1 full blown custom 260 AI. My personal ressults are that it is worth the extra effort. I can easily get an extra 150-200 fps faster than the standard 260, dont have to trim cases, easy on the shoulder, and as accurate as anything I ever shot. I still get great accuracy while fireforming.
With that being said, there is absolutely nothing wrong with the standard 260 and i doubt anything will ever be able to tell the difference of the extra speed, but its sure nice to know you have more horsepower with the AI. Either choice would be a fine one, get it started and dont look back.

I run a 260. That being said, my experience is limited due to the fact that right out of the gate, I tried what was essentially the same load, with .5 grain powder difference and found a consistent shooter in the .2s and .3s.

Mine is your basic 700 trued, with a lilja tube. Pretty typical precision rig. Topped with a 6.5x20 Leupold.

I need to explore other options though, as my load is rather slow and my intent was to run 142 SMKs at a higher speed.

For hunting, I would stick with the standard 260. For competition, the AI sounds like it would be worth a look.

I've done some research to answer my own question: the 260AI shows a 5% gain in capacity. Given that, one could expect a 1% - 2% gain in velocity (25 - 50 fps), given similar chamber pressures. If you're doing better than that you're shoving more stuffing in the turkey, which can be done with either chambering.

Ackley himself wasn't too strong on the 6.5-08AI. But if it turns your crank, go ahead.

In response to to the OP I don't think the AI buys you that much at a 1000 yards you'd need a significant jump in velocity to make much difference in wind. FWIW Sherri Gallagher won all kinds of stuff this year at Camp Perry shooting a mildly loaded straight 260.

My intent is to rebarrel my 12FTR to the 260 in the future. I was leaning toward the AI, but now don't think it's the way to go, especially if I use at least a 30" tube. I can always rechamber if it's not enough, but really don't think it would be an issue. Thanks for the help, Luke

"the 1999 British Long-Range Benchrest Championship was won by a Tikka Continental in 6.5x55"

http://findarticles.com/p/articles/mi_m0BQY/is_2_49/ai_95680073/pg_3/?tag=content;col1

I bet a 30" 260 will get you every bit of the above's performance, and then some. Terry Cross can answer your questions on the AI as he has used it alot and built many, though since went back to the Non AI, due to feeding issues.

http://www.6mmbr.com/gunweek046.html

FWIW, I use a 260 and 6.5x55. I like to K.I.S.S. for what I do.

...uh hu...150-200 fps gain by adding a couple of grains of powder...yeah...sure, whatever. I caught a 50 lb. bass on a ten 10 lb. cricket yesterday. Flinch

Horse poop.



Again, if i run the same insane pressures you are running I'll get 200 fps faster out of a 284 case.

If you say so. I have both, do you?

I attached a 25" barrel in 260 Rem to a 700 Ti action
shot it 200 rounds then AI it, shot it another 200 rounds then turned it into a 6.5-284.

Sounds like a proper 'controlled experiment' ....scientific style.

I did the same thing with a 280 Rem to 280 RCBS then to 280 AI.

At equal pressure for every 10 % increase in case capacity one can expact a 2 1/2% increase in velocity. Anything else is a pipe dream

SU35, truly, any comparison whether on velocity loss in various bbl chopped, OR various chambers and how speed is improved is no doubt, an accurate test when using same bbl.

I'm convinced that anyone who gets more than 100 fps from a AI cartridge over it's parent has really jacked the pressures up.

This thread has me pondering the merits or a heavy 260 or 6.5x47

I can give some actual data on the capacity differences. I built my very first one in 1979 while in gunsmith school and quite a few since then. I corresponded with Ackley by mail about the first one. He even sent me some load data from the Prowley Ballistic Calculator. They were way too hot!

Here are pictures of the before and after cases.



This .260 case before fire forming weighs 160.9 grs empty.


This fire formed .260 AI case weighs 160.5 grs empty.


The plain .260 weighs 212.3 grs full of water.


The .260 AI weighs 217.3 grs full of water.


The water weights for these cases are �
212.3 � 160.9 = 51.4 grs for the standard .260
217.3 � 160.5 = 56.8 grs for the .260 AI
This gives of 5.4 grs or 10.5% increased capacity. (5.4 divided by 51.4 = 10.5%)

Sorry for the bad pictures. For what it's worth, the .260 AI performs great and case life is terrific, i.e. - 10 + loadings.

Bob

PS - My first post.

Welcome to the "fire" Bobcape.

Good first post.....................


Ted

Thanks Ted. Been a member for a while, just not much of a poster I guess.

Bob

Best to start off slow! that way you don't wear yourself out! grin

interesting info! thanks for posting it up!

Paul

Dang that 260AI is sexy and I've a Rock .264 barrel on the way. That AI body is like a Siren's call though I know it may cause feeding issues.
Perhaps a center feed DBM of some make. Hmmmm.

Go for it.

Feeding from a Rem 700 SA is not bad. I use the SAUM follower. It allows 4 down and feeds pretty well. I polish the follower, feed ramp and bottom of the rails really well. You can feel it coming out of the magazine for sure, but no problem.

Bob

Ok I have to ask where did the .4 grs go? just blow out the end of the barrel? You do realize it's the same piece of brass right? just different dimensions but the same amount of brass.

You might want to check your scales. Unless it was not the same case and your cases are varying that much in weight.

Actually it's not the same piece of brass. I weighed a standard .260 and a formed .260AI empty and then filled with water. The two pieces of brass weighed .4 grs different. Sorry for the confusion.

Bob

If you wanted to get real anal the AI'd case is likely a hair shorter than the parent case. The capacity of that length difference is just bullet at like OAL, LOL.

I'll flip flop a bunch before I get all the components in the smith's hands and commit,LOL.

I've owned two rifles in this chambering, my experience has been mixed with highs and lows. Accuracy seemed ok, but not exceptional. Fire forming brass is pretty straight forward and case life was very good. The last rifle has fouling problems, after a few rounds, the groups grow exponentially and is not reliably accurate. Therefore, this rifle is awaiting a new barrel and will be chambered in 6.5X47 Lapua. The 260 rem bests the velocity of this chambering by 100 or so fps but the Lapua is far more accurate and close to the same velocity with smaller case capacity.

At higher pressures. Why don't you try out some the new Lapua 260 Rem brass.

I can't wait for that stuff to get out!

I am going to ream my 260 to 260AI, main reason is that I don't have a 260 die and I do have a 260AI die. The neck on my 260 is .294 and I hate it. The neck on my AI is .297 or 298 which will work with available brass better. I am waiting for the new Lapua stuff to come out before I do it to see if it works 'as is' before I tear this sucker down!

Any idea in how long before Lapua 260 brass is out?

Graph's says April. I put in a order.

I spoke with Terry Cross a bit yesterday and brought up the 260/260AI.
I want to be careful not to butcher what he articulated so take what I write with a grain of salt.
The gist I got is that he like to run his 139/140 grain bullets near 2900 fps(26" barrel). With better brass being available, Norma and now Lapua, He can run higher pressures and still keep tight primer pockets with the 260 and reach those velocities.
Also a rifle that feeds well may not do so in under the rigors of the field and competition and the standard 260 has a marked advantage there.
FWIW.

Which translates to about 60 fps, given equal pressures.

Fun Sucker!

True, and if I was running an 260 AI the first powder I would try would be RL25 to take advantage of that little more capacity.
I would bet 2,900 with a 140 at equal pressure.

Here's the results of a 100 grain ballistic tip that left the Muzzle at 3350 fps... and met a 175lb blacktail at 125 yds...
this was out of a plain old factory Ruger 77 Mk2. in 260 Rem...