The differences among the different types of shot is discussed occasionally on some of the modern-shotgun boards. The problem is that, for best results, one needs thick, consistent electro-plating over appropriately hardened lead (the requisite alloying varies with shot size), but some of the "plated" shot are little more than a thin "wash" over fairly soft lead, and all these give you is "chilled" shot with lower friction - they still scrub and deform on setback about like normal cheap shot. What makes matters worse is that it is often difficult to get specifications from manufacturers or dealers. There was a consensus that an unplated but hard (sometimes called "magnum") shot, of known alloy or of established good reputation, will consistently outperform lower-quality plated shot, and usually at a lower cost.
I am not current on who is making what qualities of which sorts of shot, and where it is available, so I would suggest that anyone interested should post an inquiry on some of the shotgun boards. There are probably a number of good boards with knowldegable members, but I have two that I can recommend, if the moderators permit it.
Joel
