Ok, couldn't resist temptation and dug out my collection of old original 44 Colt cartridges. I have cartridges from UMC, REM-UMC, DCC, WRACO, Martin primed, and internally primed. Out of all of 40 some cartridges, the only ones that wouldn't just drop right into the chambers were the Martin primed. Now, I may be wrong, but weren't the Martin cartridges made specifically for the early conversions by Colt and Remington? Weird.