Originally Posted by asa
TMR I am having one built right now. Dont quote me but I beleive the guy building mine said there was close to a 9% case capacity increase. He says 3050fps with a 300 smk is what they have seen. Also he said the brass does not stretch as compared to the regular 338/300. He has also built 338 lapua A.I. with the same case results.
Based on volume of water to establish case capacity 9% is what we have gained in the 338 Edge to Edge AI
Doing the Lapua AI we gained 11% case capacity.
Bear in mind water is hard to get 100% back out of the casing, but is the closest I could come up with that was a medium of constant weight that would completely fill the casings.
In my opinion having the extra case capacity means being able to gain a few more fps with the bigger bullets.
Having the extra capacity did not seem to make any real difference when shooting 250 gr bullets, yes we gained velocity but the accuracy started to fall off.
The Lapua AI thrives on U.S.869 we found. In our rifles 111.5 gr behind a 300 gr SMK delivers the best accuracy and velocity, no pressure signs what so ever, even up to 114 gr
The AI chambering seems to keep the brass from growing, in my own rifle I have 9 reloadings out of the original Lapua brass, never has it been trimmed and it is still totally useable, so I will continue to use it. Every other loading I do bump the shoulder back 1 thou, just so the bolt will close easily.