I've been weighing my bullets out of a Lyman DC #452374 in hopes of making better bullets and have been happy enough with the ones out of the rear cavity but not the front one. Suspected that the sprue plate might be part of the problem and another discussion elsewhere got me out in the shop the other day. I drilled out the stop pin and drilled and tapped for a 10:24 screw to replace it along with a 6:32 set screw to hold it in adjustment. I believe this helps the sprue plate stay flat but still allows the plate to swing freely. First test indicated a marked improvement and will be doing some further testing. I understand some moulds are made this way but I've never seen one but wanted to pass along for consideration or comments. Do wonder how those stop pins are put in as I couldn't pull it and had to progressively drill it out which was the worst part.
I bottom pour and have come to prefer aluminum sprue plates so just made another.