Does anybody know what the water capacity for the 7mm-08 AI is? Or any other 308 based AI cartridge since the increase in capacity should be similar for 243,260 and 308.

Loadtech shows 57.7 for the AI and 55.5 for the standard.

Thanks ramrod, not much increase! I measured a standard once fired Remington case and got 53.1 to the base of the neck and 56.4 to the mouth. I also found a website that said 54.6 to the base of the neck for the AI which would agree well with your number if you add the neck.

I have seen some high velocities quoted for the AI. I guess they are loading to higher than standard pressures.

Remember you can get 2-3 grs difference between brands of brass. The 308 case already has a shoulder dia of .454 when an 06 is blown out it goes from .441 to .455. In a 243, 308 etc the only real increase is the little picked up using the 40deg shoulder.

Here's a comparison chart, I don't know how close it is but it looks good....
Ackley Chart

I have seen that data before. It compares to factory. For some of those rounds that is real low pressure. It doesn't say what pressure the AIs are loaded to. From my own experience with several AIs some using a strain guage those AI velocites are very optimistic. I can't even get to them using Loadtech because it won't let me set the pressures high enough.

I have owned 13-16 rifles built with AI, Gibbs and my own improved Gibbs chambers. I believed the press for years. Then I got my Chrono and access to a strain guage setup. What I found after a lot of testing was that when you load to the same pressure in the parent and improved for the 06 based case you get a 1% velocity increase for each 4% capacity. For the larger cases it was less and for the smaller it was a little more.

Unless you specifically want an AI load the factory round to the same higher pressure. Alter your throat if necessary to allow you to seat the bullet out as far as possible test various brands of cases and use the one with the largest capacity and save the rest of your money.