Yeah, I've heard that about the Wyatt's. I used the extended box on my heavy 7 WSM; in that case it was as much about fixing the god-awful feeding as extra COAL. For reference, with the Wyatt's extended box installed the rifle now feeds superbly. In stock form (the donor was a 270 WSM M700 LSS) it was essentially unusable.
Other than losing a round of capacity, I'm not sure what there is to dislike about the Wyatt's box, but then I am not as picky about this stuff as some of you who are further down the loony road <g>.
The box mag on the Xtreme certainly looks like it has great utility. I'm coming around to the notion. I have an aversion to all things tacticool.
At any rate, I've been looking for my next project, and wanting a 6.5 of some flavor... now that I see there's brass for this one it's clearly the way to go. Pretty excited. Seems like a VERY capable package, and I love me some short actions.
