Oh my. If you search around you'll find a TON of complaints about Powerbelts, especially the light ones like yours, driven too fast. You are using nearly DOUBLE the ideal amount of powder to get best performance from this bullet! It sounds like the bullet massively over-expanded, so it couldn't penetrate the shoulder and slid up. You will NOT see this with a 200SW.
I think you will be happy with the switch to the 200 Shockwave. It is a great bullet I used for many years and will be going back to next year in my new 45cal I'm building. I would recommend starting at 80-90 grains and working your way up in 5 grain increments. My Omega had best accuracy at 110gr 777, but YMMV. I shot deer with it to very long ranges and it performed well.

The bullet on the left was about 180 yds if I recall, and on the right 208 yds. They expand well even at lower velocities. While I have never recovered a bullet from a deer shot at close range, they always exited and the deer usually went right down. This is what I like about this bullet -- it performs up close, and it performs far out.