The shotguns that I shoot the most lately are a Remington Rolling Block single shot that was converted from a Swedish military rifle, and a Baikal MP-310 over-under. The Remington is a 20 gauge with a 2.5" chamber while the Baikal has 12 gauge 3" chambers.
Most of the ammo I've been shooting has been black powder handloads with fiber wads in Magtech all brass shells. The Remington is a BP-era gun but of course the Baikal is proofed for smokeless. The main reason for using fiber wads is because my shooting has been on a friend's property and he doesn't want a bunch of plastic wads littering his field when we shoot clays.
One reason I like loading BP shells is that it's simpler. I don't need to worry about specific wad/powder charge/hull/shot load combinations. I prepare "square loads" using an equal volume of powder and shot, as is done with muzzleloading smoothbores. In 20 gauge that means using a Lee 4.3cc dipper to give me ~62 grains of powder and 7/8 oz. of shot. I have also used that for 12 gauge, which gives a light kicking load that will still bust clays if I do my part.
Pyrodex can be loaded similarly.
Cleanup is a bit more involved with BP than smokeless, but because you're dealing with a smoothbore is not onerous. I use a nylon bore brush wet with water to break up the fouling, then sweep it out using a cotton flannel patch using the brush as the jag.
If you use Pyrodex, be advised the fouling is actually more corrosive than BP fouling, so be extra careful when cleaning.
One way to speed cleanup is after say, 25 rounds of BP loads, is to shoot a smokeless trap load through the barrel. This blasts out almost all of the BP fouling.
If you're wondering how removable choke threads might be fouled, in my experience it's not a problem. AAMOF, tonight I pulled the choke tubes from my Baikal over a week after having put 50 BP rounds through it. The choke tube threads had been generously lubricated with white lithium grease. There was no sign of corrosion, and indeed no sign of fouling on the threads.
Naturally, if you run BP or Pyrodex shells through a gas operated gun, you're looking at a complete teardown afterwards. For break open guns or even pumps, cleaning isn't bad. I imaging that bolt action shotguns wouldn't present problems when cleaning afterwards, either.
To load the shells I use the "nail and dowel" method as described by Mike Beliveau in this YouTube video. It's not fast but I can do stages in batches and I'm not blasting through hundreds of rounds.
Rather than the method of priming by driving the case down onto the primer, I also have two antique tools for repriming, one for each gauge. I've found that they work better for seating No.209 primers in modern hulls than they do seating large pistol primers in the Magtech cases. The Magtech brass seems to have tight primer pockets. That's OK, IMO, because it means they'll take longer to expand and become useless.
The antique priming tools were purchased via eBay. 12 gauge tools are pretty common but the 20 gauge are less so. I had to setup a search with automated email notifications to finally get ahold of one.
Anyway, I have a brick of Winchester 209 primers and about a hundred Remington 20 gauge empties, so yesterday I decided to trim them to length so they'll chamber in the Rolling Block, and prime them.
That was easier said than done. I trimmed them using a pipe cutter with the case slipped over a dowel for support, but it's not really sharp enough, so I had to finish each case with my Swiss Army Knife.
So last night I placed an order with Ballistic Products, Inc. for their Trim Doctor tools, which is designed to easily cut plastic shotgun hulls using a utility knife blade as the cutter. This should work better than the pipe cutter.
While I was giving BPI some money, I also ordered a bag of 500 Federal once-fired 12 gauge hulls, and suitable wads and cards for reloading both 12 and 20 gauge plastic hulls with BP and non-plastic wads. (Plastic hulls have a smaller inside diameter than the Magtech hulls so I need different wads.)
Black powder loads are hard on plastic hulls so I'm expecting to get only 1 or maybe 2 shots per hull. That's fine because using them means I don't need to worry about rinsing and tumbling them, unlike the all brass cases.
If you like black powder and you like shotguns, combining the two is fun and easy.