My .260AI Story

[Joe C]

This past fall I took a trip to see my friend Bob Pastor. I wanted to build a new rifle in a more competitive round. So, while visiting I spent some time learning how to barrel a rifle. The barrels we did were chambered in .260AI and all three came in within .001" or less of each other in every measurement.

I didn't know a bunch about the cartridge and honestly, other than a few articles here and there,, didn't find a ton of info regarding load data and such. So I spent a lot of time (read dozens of hours) researching the round on line and by talking to guys like Gord Ogg who have been shooting the round for decades. In doing so my load data came fairly easily when the time came to shoot.

The fire forming loads showed groups of .5 to .75 for 5 and 10 shot groups at 300 yards. After forming the brass I tried a few powders and loads. What I finally settled on was 48.5g of H4831SC under a 142g Cauterucio bullet. It is a LONG bullet. But having the reamer from Kiff set up to allow for it with a tight neck made for a great combo.

The rifle consists of the following:
Bat Model B Multi Flat RBLP
McMillan MBR Stock
Jewel 1.5oz Trigger
Barrel 1-Brux 29" 1-8" twist
Barrel 2-Brux 29" 1-8" twist
Barrel 3-Kreiger 1-8" twist fire forming
March 10-60 BR Scope

The first match I ever shot with it was the Berger National match in February. I was very happy with how it shot considering I'd never fired at a competition more than 600 yards away.

The next match was at our local range for 600 yards. I shot a 589-28X and took second.

The next and most recent match was at the same local range (Eastern Nebraska Gun Club) where I shot a 599-31X and took first.

To say that I am happy with my choice of building a .260AI would be an understatement. I look forward to hopefully getting back to Arizona this fall and trying it out again at 1000.

I'll post pics of my rig for those interested when I get some uploaded but suffice to say, several members know "Pinky" and how she shoots.

Thank you to all the folks on here that have given me solid advice, help and encouragement.

 

[trailrider121]

JOE,

Thanks for the write on your experience so far with the 260AI. What brass you using? Also, what kind of velocity you getting?

 

[Joe C]

Brass at this time is Nosler. I've got 5 firings on some and no signs of issues and still tight pockets. When I did the initial testing it was about 35 to 40 degrees and I was getting velocities of 2880ish. According to some load software I should be getting around 2950ish now that it has warmed up outside. But I will know for sure next Tuesday as I am going to go set up the chronograph and see for sure.

 

[jonbearman]

Sounds like you have one killer of rifle Joe. I wouldn't mind shooting that one myself.

 

[vervi1jw]

The 260ai is a fantastic round. I have been shooting it for about 3 years and am on the original lapua brass still. Barrel has about 1300 rounds though it and actually shot my best score as it ruled over 1200. My original load was 47.5gr of 4831sc with a 140 amax at 2920. Have since swapped to berger hybrids and 42gr of H4350. That is around 2800 but is insanely accurate and very easy on barrels and brass. I have a shilen dgv comming soon that will get the 260ai barrel. Hopefully it gets even better!

 

[Joe C]

Vervi1jw,

What is the length and type of your original barrel? I ask as there is not a lot of info out there in regards to barrel life that I have been able to find on the .260AI. Which is also kind of the point in starting this thread, to hopefully build some more data for those that come later who look for info...

And Jonbearman, you ever bring yourself this way I'd be glad to go shootin' with you sir! You just let me know and we'll make it happen.

 

[Joe C]

Little update for everyone on this project. Went to the range today to test some loads. Temperature was about 80-85° and the wind was out of the 03:00-06:00 at approximately 10-12mph whilst I was shooting.

I'm still shooting the Carteruccio 142g bullets. These are the results I got. All shooting was done at 600 yards in 10 shot groups.

48.5g H4831SC (this is a load that has actually been shooting very well for me including a recent 599-31)
BR2
H-2885
L-2840
ES-45

48.5g H4831SC
Wolf
H-2892
L-2872
ES-20

49g H4831SC
Wolf
H-2920
L-2902
ES-18
(Produced a nice round group with about 3" of vertical)

49.5g H4831SC
Wolf
H-2941
L-2925
ES-16
(Group had two fliers, one mine and one from a strong gust. The other 8 shots were in a group about 3" wide by 1.25" tall.)

 

[trailrider121]

Joe,

This is not a 260AI, but its a 260 rem. I using a match chamber with .160" throat, 140 hybrid, lapua brass, H4831SC @ 46.5grs, Wolf LR primer, .016" off the lands. 24" barrel and is getting 2808 avg with 10 shots, and ES 14 / SD 4. This a warm load, but it works so darn well .

Okay, my next node should be around 47.9grs ( 3% per OCW) which is impossible with my combo, and the next would be 49.4grs. as next ocw. So your 260AI seems to be real close. I know every rifle and combo is different. Now this is just a guess but your 49.5 seems to be shooting well. Maybe do a seating depth test in .003", just a thought.

 

[trailrider121]

The 260ai is a fantastic round. I have been shooting it for about 3 years and am on the original lapua brass still. My original load was 47.5gr of 4831sc with a 140 amax at 2920.

Even vervi1jw load is real close.

 

[Joe C]

Trailrider,

Indeed what you say is true. What I also found very interesting was that the Wolf primers would make that much of a difference. I'm just glad I have a lot of them. 8)