Fiocchi makes the only loaded shells available in the US. They come 2 1/2", 11/16 oz of 5,6 or 8. They use traditional nitro cards and felt wads. It is roll crimped. The lead is soft and you have to scrub your barrels. Recoil is very mild. It seems to be tuned down for older guns.

Ballistic products has all the supplies. They have a modern Gullardi (Italian) wad that is great. It has petals and cuts leading to zero.
Order a 20 gauge roll crimper. It will handle the 24 just fine. Ballistic Products has card-over wads for closure.

The factory load is only 11/16. It makes the gun shoot like a low performance 3" .410. I use the factory ammo for Skeet just to get the hulls emptied. There are 3 hulls to choose from; Fiocchi, Cheddite and solid brass (Magtech). Expect only 2-3 reloads from Fiocchi hulls.

Traditionally the load is 13/16 oz. With the modern wad you can load up to 13/16. This puts the gun into 20 gauge territory. 13/16 of #8 1/2 is virtually the same pellet count as 1 1/8 of 7 1/2 (~380).

For the typical ranges we shoot sporting clays 13/16 of 8 1/2s shoots right up there with the 12s at clays. It totally mystifies folks how that "obsolete" gun can beat them.

I created a load by extrapolating between a 20 gauge 7/8 oz and 28 gauge 3/4 loads to guess how much powder to use. You'll find it works. I cannot remember my load right now. I have used Dupont PB and Universal Clays. I'll go out and check my notes later. It seems like it was the same bushing, I just swapped between PB and UNI-Clays. I didn't perceive any performace difference.

I converted a 28 gauge MEC reloader to handle 24 ga. I used a Dremel moto-tool to open up the sizing ring. The primer station is fine. Get a 20 gauge wad guide. I broke some of the petals out of the wad guide so it would go down into the smaller hull.

I opened up a 3/4 oz shot bar with the dremel. 13/16 oz is about 383 grains on my powder scale. It took some trial and error to get the bar right.

Joe