I've got a 52 Oliver 99, and it has the M&amp;W Add Powr kit in it, all of my rings are good, except the two top ones that were rusted to the piston. Where could I find some new rings, and is M&amp;W around any more to find new ones? It has a 5&quot; bore and the top ring is .10&quot; thick and the second compression ring is .12&quot; thick. ANy help would be greatly appreciated, thanks in advance.