Rabbit posted pics and info about Lee Shotgun slug molds on Remington 870 Forum:

Hello Vitaly,
I do have some experience with the Lee 1oz slug mold in 12 gauge. I cast the slugs out of pure lead and load two different loads. The first load is the one recommended by Lee in the data sheet that comes with the mold. The load that I used was-
1 oz Lee cast slug
Hull-Remington STS 2 3/4″ Premier hull
Primer-Win. 209 primer
Powder- 38.5 gr. Accurate #5
Wad- Claybuster copy of WW12SL

The data sheet lists the velocity of this round at 1535 fps, I believe it! This round is meant for deer hunting, it is very powerful. I made a few boxes, I don’t think I will make any more. I was looking for a Cowboy Action style of slug load, something that was more like 1,000-1,100 fps. I asked a good friend of mine who is more experienced than me, he is a member on a few forums and he sent me this recipe. It is more like a light bird hunting load and is my go-to slug load now.

1 oz Lee cast slug
Hull- Remington STS 2 3/4″ Premier hull
Primer- Win. 209 primer
Powder- 15.7 gr. Clays
Wad- Claybuster #CB1100-12

Here are a few pictures of the Lee mold and slugs, and my reloading set up.

Lee Shotgun Slug

Lee Shotgun Slug

Lee Shotgun Slug Molds

Lee Shotgun Slug Molds

Lee Shotgun Slug Molds

Lee Shotgun Slug Molds

Lee Shotgun Slug Molds

Lee Shotgun Slug Molds

Shotshell Reloading

Shotshell Reloading

Recommended Slug Molds:
Lee Production Pot IV

Lee Production Pot IV

You can get Lee Production Pot IV on Brownells
Lee Shotgun Slug Mould

Lee Shotgun Slug Mould

You can get Lee Shotgun Slug Mould here: Brownells