The barrel may be more of a limiting factor than the mags. One of the truncated cone bullets that I used had to be loaded really short until I had the barrel reamed. Be sure to check that along with the mags.
A course in any USPSA match cannot require you so start with gun in weak hand. If you choose to do so, that is your option.
Not using a HF, but Seekins and the push button safeties have served me well.