While back I experimented on sprue cut for PB. Thought cold cut would give a good solid cut. Well, it does but had problems with the sprue plate lifting and NOT a good cut square to bore. Result was a nice roundish pattern @ 100 from BO pushed hard. The small divit in the base works better. I also found gravity drop of the mould on a hard surface immediately after pour helps with good base fill. I do not use larger than 2x mould for rifle due to cooling problems. Quality over quantity every time.