Anyone shoot this round, and what, if any advantage would it have over a stock .260rem.?

Since the parent case, the 7.62 Nato (.308 Winchester) has little taper to begin with, and a 20% shoulder, there's not much to be gained by "improving" it. My guess is less than 5% case capacity increase or so. In my opinion, not really worth it. The boys who claim big increases from their .243 AI's and such are mostly benefiting from and increase in testosterone resulting from foolishly packing more powder than is wise into the improved case. Higher pressures = higher velocity. Always have, always will.

Now, if you want a "ringer" in an improved short case, go the the 6mm Remington/ 7 x 57 series. That case has enough body taper and a long enough neck that blowing out the shoulder and moving it forward can make a real difference.

I would estimate from 75-100 fps increase with 24" bbl..... I don't have a 260AI but have a 25-308AI and 7mm08AI. I really like the Ack Imp case!!!

Thanks for the input guys. I was thinking it would gain about 100fps across the bullet weights. I am narrowing down to the 6.5x.243imp. or the 6.5x.284. I need some gundmith input.

Stonecreek,
Go easy on the 243AI. It is a good one for specialized applications such as bombing coyotes and bobcats way out there. You don't have to load em hot to get the performance, at least not in the 243 version. sure-shot

Go with the 6.5-284 as it will give you the advantage of the heavier bullets. You can shoot the lighter bullets like a laser beam and heavier ones work well for deer and long range target shooting. Very accurate cartridge worth considering.

I think stonecreek has it right. what is 100fps gonna gain you????? A lot of the ai's just mean a bunch of shop time forming cases that could be spent shooting. 'course whatever peels your bannana..........