Excellent mold. The wheels are a bit difficult because the metal does not flow in every spike of the wheel. But with the help of some miliput two component clay the problem is easily solved. The result was a very beautiful four horse 6 pounder gun limber. Prince August Response. The wheels have vent holes applied. You can drill more if they seem insufficent. Tapping the mould helps too. Cleaning the area where the vent holes are between castings so the holes do not get blocked with release agent can help.