Ive not loaded for that round, but I do load for the 28 nosler and several 300 and 338 rums. That said, it has been my opinion that there is no appreciable difference between 28 nosler and 7 rum with barrels of 26" The 7 rum holds 8 or 10 more grains of powder, but really should have a 28 or 30" tube to capture it. that said, the 338 rum is a tad shorter than the 300 rum, so your wildcat should hold a couple grains less than the standard 7 rum. In the same 26" barrel, I would think 28 nosler velocities would be really close to what you end up getting. I run the 28 nosler with 150s over 3400 fps and have not tried any lighter bullets yet. I would think any powder that works with those weights in the 28 nosler will work for your uses. My 150 grain load is on RL26 and there is plenty of dead air in the case, so a smaller case should accomplish about the same thing. Stepping up to 175s and 195s, I am with RL 33 and 50 bmg respectively. The lighter bullets usually do better with quicker powders, which you can use as much of, so I expect you to have a low case fill % when you hit pressure.
Keep us posted with what you figure out. Would be interesting to hear about.
