It depends what I'm up to. In my 16ga, I usually use FFg or Ctg for the charge, and at most equal volume to the shot charge, often somewhat less to tighten the pattern.
1oz of shot over 1.3/4-2.1/2dr powder
1.1/8oz " over 2-2.3/4dr "
1.1/4oz " over 2.1/4-3dr "
I haven't played with 3/4oz loads yet; for that, it would be 1.1/2-2dr of FFg. I might try 1.1/4-1.3/4dr FFFg with that light of a charge, too.
I use multiple overshot cards rather than a 1/8" overpowder wad. With my somewhat rough bores, I need more thickness do than some do to seal, 3 minimum so usually 4 of the normal .020" ones or equivalent home-punched from cereal box, shotshell box, etc., or 5 punched from milk cartons. Again, the rough bores NEED lube or loading quickly becomes impossible, so I always use either a lubed 1/4" felt or fiber cushion or I spritz some moose milk in before inserting the card over the shot. Paper or card shot protectors is a whole 'nother topic (I usually use something of the sort).
Regards,
Joel
p.s. if I ever HAD to use steel shot rather than lead, bismuth, or NiceShot, the load would probably be something like 1oz over 3-3.1/4dr FFg, with the usual caveats about bore protection and likely 5 O/P cards. Even that is likely getting stiff for the stock on a 7lb double to put up with.