rcslotcar
coww's can present problems. Hardness for the speeds you are shooting may be also a problem. I am not sure, but some already shot hard alloys but I think they may have been harder than yours. May be others can advise on these matters.
Also, some wheel weights have impurities, that can cause adhesion problems with coating.
I don't know if you have been following this thread long, but another guy has all sorts of coating problems using mystery alloys.
He solved coating problems by casting, then soaking casts in Hydrochloric acid/water mix, to remove reactive surface metals. The coating then bonds extremely well after washing with water and drying first.
It is not the coating that fails, it is the alloy that may fail if not correct things are done first. Keep in mind, the coatings are a way of separating bore and alloy.
Coating cannot fix engineering problems. It cannot be compared to Jacketed ammo requirements.