You don't have to know about metal ratios and alloying for using WW's for handgun bullets. Use 100% WW's and if you have problems with the mould filling out making perfect bullets with nice sharp edges, that's when you add some tin to it. Tin can be had in rolls of solder 50/50 is cheapest. I have a 20 LB pot so I use about 18" of solder for a full pot of WW's. This helps mould fill out.
Learn to be a picky bullet caster! Reject the bad ones and remelt them later. Watch for perfect bases on the bullets, nice and square, not rounded.