The Lapua mag in the Remington 700 is 3.375+ in length. My buddy has had one on order for over a year. He finally gave up and ordered an Accuracy International magazine. That didn't work out so well, right length wrong width, he returned it and got another one, only this one was the right width but wrong length (3.325).

Here's the bubba fix. steel spacer and JB Quick.

A little bulldog prep and some black paint and it'll be done. One note. the AI has a square follower sort of like an old mauser, so you can't close the bolt on an empty mag.