I took a close look at several of the "newer and better" chamberings several months back.
My conclusions were that the 243WSSM was the least of the bumped up vels of all the WSM/WSSM line of offerings. Feeding these short stubby rounds in a AR platform can be a little "tricky" also.
I would pick a 243AI over the WSSM if I had a choice.
NOW . . . the 270WSM is another story. That is the one that I picked for a bolt gun.
Remember . . "compete with" velocity is one thing . . "compete with" accuracy is something all together different.
Interested in what you find out and deciede to go with. Let us know please. --- SAWMAN