Re: 300wsm not sure
I sometimes shoot 210 Bergers out of my WSM. When I seat them to the lands only about 2/3rds of the bearing surface of the bullet (between the neck and ogive) catches the neck. I dont think that I would be able to load 190 Bergers to the lands in my rilfe very well which is a Sako. The SPS *may* be different? You will have the same issue with the 7mmWSM and long skinny bullets.
I like the 300 WSM becuase it has a little more thump than the 7WSM. They both have about the same trajectory and range. You will get a lot more barrel life out of the 300 WSM.
If you want to load to the lands in a short action, you need an after market mag box. Another option is to get a long action and have it barreled and chambered to the WSM.
Hope that helps,