Most flatlanders i encounter in the hills get wiped out by altitude. There's not much in the way of training is gonna help with that. Acclimatization a couple days ahead of actually hiking will really help. I like to sleep at higher elevation for at least a night. Proper hydration will also help...
Was thinking about getting the wife hooked up w a stoeger. Maybe not.
Im running a franchi affinity 3 and it runs anything I've put in it. First shells i ran through it were light field loads and it ran all 100 rnds without a hiccup.