I'm surprised no one has addressed this. Speaking from a firearm perspective...
Lubing lead bullets in black powder arms has been done for centuries. Lard was the lubricant of choice many years ago. Now, synthetics are being used. Low velocity centerfire cartridges often use leads bullets, but most of the time they also use gas-check discs. But all of these bullets are propelled by gunpowder, and typically in a steel barrel.
We all know that a run-of-the-mill pellet rifle have a brass barrel. Lead against brass is slippery enough that lubricant isn't necessary. And, as you point out, may indeed cause dieseling. This doesn't address the steel barrels! Since I don't have experience with this specific issue, I can only guess what is appropriate. I suspect, it depends on the lubricant. For example, beeswax has been used, and I don't think beeswax will diesel!
All this said, I'm playing around with Danzac (Tungsten DiSulfide). It works much better in firearms than molybdenum disulfide, and without so much rub off issues. One thing is for sure. Danzac-coated pellets average about 10% lower velocities than uncoated ones, which means the stuff increases the slipperiness of the pellet's barrel transition time.
Of course, this means I need to mod the valve unit, to allow higher pressure (more pumps), so stay tuned!
