Originally Posted by 338Federal
So, nobody has yet given their actual measured increase in fps. Lotsa talk about pressure, bbl length, strain guage, non-stretch brass, etc. I'm just curious how much faster, measured, the AI really is.


Barrels aren't all the same and velocity can differ quite a bit with the same load. I haven't rechambered a .223 to AI and checked velocity increase.

Some accuracy loads with standard .223.....14 twist 26" Shilen, 50's at 3640 and 40's at 4010. A 12" twist H-S, same reamer, gives identical velocity. A 20" .223 with very tight chamber, working load is a 403895. IMI brass, AA2015 or VV133.

A 14twist .223AI.....load is 50's at 3825, 40's accuracy from 3950 to almost 4200. Depending on powder and bullet. IMI brass, AA2015 and VV133.

Increase is 150-200 fps. with lighter bullets. It's not just because of powder increase, which isn't huge, I believe it's also case shape. With a standard case best accuracy is usually when you back off some. The AI case with 40* shoulder and less taper likes to be accurate with top end loads. The accuracy window seems to be larger too.