I picked up a couple black powder molds. They have aluminum handles and black anodized aluminum blocks. One is a hollow base 58 cal and says A 577 on side. The other appears to be 54 cal and says D 541 on side. Does anyone know anything about these? From looking around on the internet they appear to resemble the blocks of Thompson Center, but I have never seen any of their molds that look like this. Did they have cast aluminum handles?