So with winter here, I'm sure a lot of casters will be casting and taking the opportunity to make a good supply for the future. I cast on a needs basis which has included many times in not so cool weather; so is there any differences?
Very much so, in temperate times (Feb & Oct) I find I can run up to 6 moulds and get good results. In the cooler months, I limit activities to just 3 moulds. The reasons are simple, out of winter, the moulds will cool more slowly so allowing time for the sprue to harden and gives more time to fill another mould.
Winter on the other hand, allows moulds to cool more quickly and throws open the possibility that the sprue hardens and actually tears away from the bullet instead of shearing like a knife.
Timing is most important to good results. Perfect and square bases are necessary to have good bullets and also for gas checked designs, that the gas check will seat perfectly square with the bullets central axis.
Perfect bases are a must for good bullets.
Gas Checks must be square to the bullet axis