It will be mainly for sabots. At this point sizing and shooting sabotless doesn't have a lot of appeal.
It looks like Douglas barrels in .50 can be had in 20, 24, 30, 34, and 36. So if that's the case my options that I would consider most are 24 or 30, and I'm probably leaning more towards the 30. I need to talk to Ron at SMI again and see what I can find out.
Grouse, I thought long and hard about going with .45. In the end I decided that I have exactly 10 .45 bullets and boxes of .50. If I had more 40 bullets and 45 sabots around I would go .45 for sure.