Indoor ranges are where 90% or better of my range scrap came from, so I may be able to help out a bit here. My average recovery from a full 5 gallon bucket of indoor scrap averages right around 100 lbs. Most of the buckets weigh around 125 lb, so be prepared for some waste. Like most guys, I do my melts in a cast iron Dutch Oven over a propane fish cooker. Pretty standard stuff so far. I use a small garden trowel to fill the dutch oven almost to the top. There will be a lot of trapped air in the scrap and after melting your pot will be about 2/3rds full.
I use a surplus military mess hall serving strainer to separate the trash from the lead, you will see what appears to be a lot of dirt in the scrap, a lot of it is actually fused, unburnt powder, and it has never been an issue that I was ever aware of, it has all been inert every time I've done my big melts, but I think it's best you know what it is. This information came to me directly from the owner of one of the local indoor ranges, he was also the guy who swept the floor, cleaned the traps, and carried the heavy buckets out for recycling. I consider him a first hand source of this sort of thing. He said his floors were swept several times a day, range traffic permitting, and there was no way this was ordinary dirt. I tried to light a few samples of it early on and it simply wouldn't ignite. BTW, his floors were the dirtiest after small bore matches, he claimed 22 LR was the biggest offender of all.
Strainer.
The strainer is the cleanest way I've found to separate the trash from the lead, a picture is worth a thousand words, and that certainly holds true here. Just scoop up the jackets and the trash and deposit it in empty metal containers to give to the local hazardous waste disposal amnesty program. You can try to separate the jackets and sell them for scrap, but I've never has any success with that. All mine gets tossed with the dirt. YMMV.
At this point you'll know what to do next, flux the hell out of the remaining lead and don't forget that there will be trash trapped between the bottom of the pot and the lead itself. I usually ladle the clean lead out into ingots, but leave 1/4 inch or so in the pot. I'll let that cool, then remove it later and set it aside for the next time I melt. The piece I saved from the last melt goes on top of the next batch to separate the usable lead from the trash. For that matter, you could also simply pour the last 1/4 inch from the pot into ingots and recycle them that way.