Get a hold of Pat Marlin over at castboolits and see if the 44 PB check makers are done. I dont think they are quite yet, but should be close.
I have the 35 PB check maker Snuffy was talking about, and it does work very good. Make them from aluminum cans or you can but the material if you want. I aint tried these on a hot 357 load, but I have tried them with hot 9mm's that leaded the barrel full length with PB boolits. After putting on the PB pop/beer can checks, the leading was no more and they shot accuratly from the pistol and carbine both.
The tool is about $80, but it dont take long to pay for itself if you do much shooting and you can use it on ANY 35 cal boolit, from 380 on up.
I think the 44 PB would work great to, and will probly buy one myself in the near future. But, since I am out of 30 cal gas checks I'm going to order a 30 cal check maker first.