Use any of them, you'll be ok. You'll want to use fiber wads, the plastic wads will melt making a mess in the barrels. Circlefly makes them for BPI or Precision Reloading. I use a Mec 600 single stage and like [ for the 12ga - don't have a 16 ] 10ga OP wads, 11ga cushion wads, and 10ga OS cards. With the Mec enough pressure can be generated to load the larger sized wads for a nice tight fit. In a 16 you could go down to 14 and 15ga wads, if you wanted. This was all in Magtechs which are thin walled so the inside dimension is larger than a regular shell. If you're gonna be using the turned shells then they will have a smaller ID and you'll want to go with their recommendation. Any white glue will work to glue the OS card in place. With plastic shells I just use 12ga wads in the 12ga shells and with a fold crimp you won't need the glue.
I've shot both nitro, BP and subs for many years without problems. The extra pressure T7 or Pyrodex might generate is not enough to worry about. I have about 15 old SxSs - Parkers, Remingtons, and a Lefever ; all but three are Damascus [ Pattern, Twist, and one Laminate ] , and one or the other gets used shooting clays three times a week. Normally it's nitro, but for SxS events BP is usually used.
In the 12ga I often use just 70grs of 3F and 1 oz of shot to save money. The 3F burns a little hotter so less is needed. It makes a difference if you're gonna be shooting a 150 shells in one day. Good luck and have some fun.
