Howdy
A couple of things. There is an old rule of thumb called the Square Load. Basically, a Square Load is one where the Volume of powder equals the Volume of the shot. Nothing to do with weight. If one tries to put in more powder than shot by volume, one risks over powering the pattern with too much powder, and the result can be blown patterns. But if
less powder than shot, by volume, is put into the shell, there is no risk of blown patterns. Just lower velocity.
My standard load is Winchester (or any other brand) #209 primer, a 4.3 CC Lee dipper of FFg (whatever brand I have on hand) followed by a Circle Fly 1/8" over powder card, Circle Fly 1/2" fiber cushion wad, 1 1/8 ounces of # 7 1/2 or # 8 shot, and finally a Circle Fly over shot card, all stuffed into either a Winchester AA hull or a Remington STS hull.
The reason I like those hulls is because they are smooth and slippery and eject the best from a SASS legal SXS shotgun without ejectors.
Regarding the powder charge, it is simply the biggest dipper in the Lee set. It weighs out to around 60 grains, depending on the brand of powder. This is only about 2 1/8 drams. Plenty of powder to get the shot out of the barrel and smack down any knock down target I encounter. This is well shy of a Square Load, but it is shy in the powder department, so there is no problem with blown patterns. In my not so humble opinion, more powder than this is a waste of powder. I only get four boxes of shells to a pound of powder, and powder ain't cheap when you are loading a lot of it.
I do not use a lubed wad, all my wads are dry.
Soft bullet lube is for rifled barrels. Without soft lube, fouling can build up in the rifling grooves and ruin accuracy. But a shotgun barrel is just a pipe. There are no rifling grooves to fill up. Basically what happens is the wads will scrape out most of the fouling left behind by the previous shot. The small amount of fouling in the bore does not affect the pattern. Getting the fouling out is easy with either hot water or Murphy's Mix.
However if one chooses to use a lubed cushion wad, a dry over powder card on top of the powder will prevent lube from getting into the powder.
As to why I add the over shot card at the top, my load does not completely fill up the hull. Without an over shot card, my crimps are a bit concave and shot can escape. So I add the over shot card to keep all the shot in the hull. No, a 1/32" thick over shot card does not affect the pattern. Yes, I could add more powder to fill up the hull a bit more, but I have already mentioned my opinion about that. Over shot cards are cheaper than powder.
Most BP shooters in the CAS world do not go to the added trouble of separate wads as I do. The standard plastic wad for 12 gauge Black Powder loads is the old Winchester Red Wad. Just the right size for plenty of shot, and the increased powder volume you get with Black Powder. Winchester stopped making this wad a few years ago, but Claybuster makes a good substitute for it. Yes, plastic hulls do leave melted plastic behind, but it is not very difficult to remove with hot water and a little bit of scrubbing. I can tell you that very few Cowboy Shooters go the separate wad route, most use plastic hulls for the convenience.
One other thing about plastic vs separate wads. Modern shotguns have longer forcing cones than 19th Century shotguns had. A plastic wad is longer and will bridge that longer cone better than separate wads will. Separate wads have a tendency to tilt in a long forcing cone, which can also affect the pattern.
Regarding brass hulls, paper hulls, and other 'period correct' (gawd I hate that phrase) hulls, in CAS we go through a lot of shotgun shells. Probably close to two boxes at every match. I am much too busy loading up all my metallic BP ammo to be concerned about loading up more historically accurate hulls. Loading brass hulls takes a lot of time, and they are very expensive. Same with paper hulls, the hulls need to be trimmed and then roll crimped. I just use my old MEC Jr and crank out about four boxes of BP hulls an hour. Loading more historically accurate shells would take much longer.
Here is a photo of my lovely old Stevens hammer gun that I usually shoot in CAS.
And here is a photo of me blasting targets with it. Yes, the glove is because the barrels get very hot on a summer day and the tiny splinter forend does not protect my finger tips from getting burned.