Origins
And therein lies the origin of cartridge conversion revolvers. This wasn’t just limited to Colt revolvers; some gunsmiths also got in on the act. Using barrels originally made for their cap & ball revolvers required the new metallic handgun cartridges to carry bullets similar in diameter to cap and ball projectiles.
So, some bright light decided revolver bullets should be made with two diameters. The main bullet segment would be full size in the same diameter as the outside cartridge walls. Then, the base part of the projectile was made small so as to fit inside the case walls. These bullets came to be unofficially named heel-base.
Lead alloy bullets need lubricant, so knurling or grooves were put around the outside portion of heel-base bullets, and bullets were dipped in melted lubricant.
Sometimes, no knurling or grooves were applied. Instead, a card wad (thin wafer) went over the black powder, then a one-eighth disk of lubricant set atop the card wad and finally, a heel-base bullet seated. I actually have some old factory .44 Colt loads assembled like that. I pulled some apart to examine them.
There were many of these early metallic handgun cartridges, but space won’t allow all of them to be detailed. If the above paragraph has you confused, just look at a round of modern .22 Long Rifle. They are still made with heel-base bullets and dipped in lube.
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