Go to "Products and Prices" then to "configure a mold" in the left bottom of the "molds" block and from there you custom order the mold you want , you will select mold body metal, for a machine or hand casting, the # of cavities, sprue cutter type you want and mold number (write down the mold # you are wanting before you go there so you don't have to go back and find it.).
There you can also make any mold changes you want like : diameter, bullet length, grove depth, ect... that you think would be better for your gun barrel.