Ken, Sorry, I’m not sure who “Mr. Nelson” is, but there are several .513 molds currently on the web site. None are available. Although, if a new mold is being considered, a .515 bullet with a hollow base would be great. It could be sized to .513, .512 or .510 allowing for use in almost any 50 cal cartridge. By default the weight would be around 450 gr. give or take.
Mark Al owns NOE, He is working full tilt. I am sorry I misunderstood your post. Keep checking back. His molds are in huge demand and often sell out pretty quick. With all the designs he offers it is nearly impossible to keep everything in stock. Next time I talk to him on the phone, I will ask him about the .513 stuff.