My mistake, I found where I read that the 12 was large shank, the reference only specified the LRPV model.

Is there a large weight penalty or other drawbacks for a large shank action?

Can someone clarify what they're referring to about the bolt head regarding the wsm cartridges?

It seems there are more aftermarket stock choices for the short action, is that accurate?

Right now I'm torn between a 308win, 6.5-284, or 270wsm for the build. So it seems that:

SA small shank is only appropriate for the 308
SA large shank is appropriate for 308 or 270wsm
LA small Shank is appropriate for the 308 or 6.5-284