Whats the diiffernce

[Heavvyduty]

I'm just a varmint hunter here, But i was just wondering when you guys say 223AI or 22-250AI.
Wat doz AI stand for . I know it must be for better accuracy but how much better. I'm shooting a standard 223 savage predator10 and it cant get to much more accurate, So wat doz a AI barrel give ya?

[Der Verge]

AI stands for Ackley Improved.  There was a gunsmith not too many years ago named P.O. Ackley that decided that he could make standard cartriges better.  While he greatly improved the velocity of some, others did not improve so well.  Either way, the best part of what he did is that you can take a standard round, say .223, and fire it with out any issue out of a .223AI chamber.  Actually, that is how you fireform brass for your Ackley chambered weapon.  As an example, 55gr bullet in .223 standard velocity is 3200-3250,  where the AI will give 3400-3500.   All properly done, anyway.

[Fjold]

"Improving" a cartridge involves taking a reamer and opening up the body dimension of the factory chamber to take the taper out of the case body and sharpen the angle of the shoulder.  The new improved cartridge will have more capacity than the parent cartridge and the new cartridge should headspace at the same point as the parent cartridge.  This allows you to shoot factory cartridges in an "improved" chamber and then reload the improved cartridge for higher velocity than the parent cartridge.

The old rule of thumb was that for every 4% of increased case capacity you will see 1%  of velocity increase.  With the sharper shoulder you should also see less case growth during firing.

[Heavvyduty]

OK so its for VELOCITY not ACCURACY!!!

[CJ in WY]

A side benefit is that the AI case tends to not need trimed as often and in most cases not at all. About the only down side is they dont feed out of a magazine near as well.
As for accuracy?? Usualy an AIed round will be more accurate due to tighter tolorances on a custom reamer and it being chambered by a smith instead of factory but?

[Der Verge]

In theory, it is only an improvment in velocity.  In reality, accuracy can be improved also, but only because of the custom cut chamber as CJ said. 

So, yes, velocity......
and....