I think you would have a hard time finding a better round for mule deer and antelope than the .270 WSM. It looks like you just had poor bulet performance on your doe. Load some ballistic tips or buy a factory load with a similar bullet and your results should be a lot better. Also a good old Nosler partition 130 gr would serve you well even if itsnot really needed on antelope, I find they still transmit plenty of shock while losing the nose section.