Free: Contests & Raffles.
What specific info are you looking for? I load Bismuth, Hevi-Shot (Tungsten), Tungsten Matrix. And lead. Basically you don't want any of the Tungsten shot touching the barrel, which usually means a taller, thicker cup. If it touches the bore it can score the barrel. The jury is still out on whether it actually has a detrimental effect other than cosmetic. Other than that, don't shoot it in a choked barrel tighter than light mod. On a single barrel gun with a tighter choke it will just hammer them out to light mod eventually, and leave a shiny ring on the outside of the barrel where the choke starts. Any double barrel (soldered) it will break the barrels apart eventually, starting from the choke end. Most of the manufacturers have load data you can follow. One caution I will give is shotgun shells DO NOT have the same 'pressure signs' as metallic, and if you do not follow load data you can have dangerous pressure and not know it. There are a few people around that can pressure test loads for you 'for a fee'.