I've got sort of a mystery here with a bullet that I have shot for many years and now it's leading the barrel just in front of the chamber. I used to use Zambini Red Rooster until my supply ran out and started using Thompson Blue Angel. All of the shooting I did back then was waay before Al Gore invented the internet and the selection of a bullet lube was based on word of mouth and personal experience. I know there are better lubes out there now but I'm about to take off down the powder coating path and enter the 21st century. I've dusted off all my casting equipment and I'm ready to get started again but I've got several hundred bullets left over that I've been using to come up with a bullseye load. I should probably throw them all back into the casting pot and start over with PC but I'm curious as to why my old load is now leading the barrel.
The bullets are cast from COWW, sized to .401" and loaded on a Dillon 550 that I bought about the same time I bought the Delta Elite. A pulled bullet from a loaded case measures just a hair over .400" so I know they are not getting swaged waay down during the seating process. Cases are well-worn Remington but I do have a fresh batch of Starline. I'm shooting 5.6 grains Unique that chronograph about 950 fps. It used to be said that shooting lead bullets under 1,000 fps would keep the leading demon away but that was obviously heresay.
I would be delighted to hear what the castboolits tribe has to say about this issue.