Hello elktaker,
I've shot 7 wsm since it came out in 2002. I've burned up four barrels on mine, and I'm shooting fairly consistently with it. I've reloaded it and worn out 300 rounds of ammo shooting it. All that to say I have lots of experience with shooting it, and loading for it.
May I suggest something that might help. Take a flashlight, or other strong light... shine it into the necks... check out to see if the brass is marked by vertical streaks. This is especially evident after a clean case comes out of the sizing die. I found that my Winchester brass had numerous imperfections inside the neck that could be measured with a very, very sensitive ball micrometer. I took the path of least resistance, literally. I use two electric drills, one with a worn bore brass brush coated with brass wool (available at furniture refinishing locations) and the other drill has a Sinclair Driver (#749-003-251sy) and Caseholder (#749-002-490sy). Put driver in its drill, put a case in it, put the brass brush in the other drill, put the brush in the neck, turn on both drills and polish the inside of the necks for 15 seconds or so. The idea of two drills opposing each other is that the even-ness of the case neck thickness is not compromised that way. No polishing more on one side than on the other in other words.
Question... have you measured your neck dimensions after coming out of an "expanderless" sizing die? It could be that your full length die neck dimension is squeezing your neck dimension way too small. That happened to me with RCBS dies, but was quickly "fixed" by going to Forster dies. Forster bullet seater is great by the way.
These two simple techniques have been key parts of my reloading for the 7wsm. Hope this helps, and if interested in more, send me a pm.
Good shooting.
Coach