I used Longshot for my 1-1/4 bismuth loads. Came out of the Lyman 5th Edition. If I remember right there was some lighter loads that used Green Dot for bimuth in there. Might work good with 4's.
Yep Bismuth is pretty easy to get good performance out of , with 1300 fps being about right for this shot density , there are other powders that will push it along at this speed quite easily . To name a few Herco ,800X , sr4756 , Blue dot , Longshot , Pro Reach and several more but finding the recipe that suits your needs , really should be one that's been tested and listed by the powder manufactures just to be on the safe side of using it !
I tried the recipe from Alliant that uses a 3" Fed hull, 1.375 oz of bismuth and 46 grains of Blue Dot. I'd say it was over pressure. Pattern was blown.
Wow ......46 grs of BD is really out of my thoughts as I've used 34 grs in a 1 1/4 of nickel #7's for some long yardage games shoots , that were Buffered !