I clean my moulds with dish washing soap and a tooth brush " just for that job". Then I heat it up on a stove to get it hot and dry, I use a birthday candle to lube the cutter. I have a drip o matic lee production pot. To be honest the bottom pour will not fill the mould fast enough. I laddle big bullets. I also try to squeeze the handles the same every time.
If your seeing different sizes your mould is not filling out. I am betting on a couple things. The lead and mould are not hot enough, AND the bottom pour is not flowing fast enough and if your not already doing it keep the mould close to the spout. If it were me I would laddle those big bullets. Ron