I learned about PB unintentionally. In '76 a local sporting goods store discontinued their gun/reloading department because their gun expert left them to open his own gun shop (all other personnel in the store were "team sports" types)
I bought 4 Lyman 4 cavity molds for $12.50 each, 2000 Hornady primers (cost ?, but cheap) and a case of PB for $2.00/can.
It was clean burning, easy to meter & was very similar to Unique (but cleaner). I used it in .45 Colt, .38 spec. &.45 ACP. My shooting buddy finished 14th OA in the '81 IPSC national @ Hampton, VA using PB & #452374 boolits that we cast in my garage. It proved a real advantage in the simulated night shoot stage because the muzzle flash was less than any power we had used (we had advance notice of a simulated night shoot stage).
I haven't been able to get any in the past 5-6 years & assume that it is out of production. I now use HP38/231 & Red Dot in it's place for the .45 Colt and HP38 & WST for .38 spec. & .45 ACP).
Henry