I am in the process of modifying 50-70 Government cases to provide 56-50 caliber cases to reload for an original Spencer Carbine. While Starline makes 56-50 brass, their rim diameter is not wide enough to provide reliable ejection. Since the rim of the 50-70 is just right, many Spencer shooters are using them. And, most Spencer shooter are reloader, as I am, but not fully experienced with a full range of reloading experience. That is why I thought to bring my questions to this forum. No concerns with cutting the longer case and trimming to proper length. Been doing case trimming for years. But, I have never had to address case wall thickness in the past. This is a concern with the wall thickness of the trimmed 50-70 in the chamber of my carbine. I have an additional thickness of .006 inches in total diameter due to the thicker wall thickness when compared to original Spencer rim-fire cases. Not much but chambering and extraction is difficult. My question is the best next step, outside wall trimmer or a neck reamer? I have no lathe to secure the case so I expect to use a Forster or Pacific trimmer to hold the case. With that simple set-up, outside or inside? Cost, outside or inside? Since a 50-70 case is over $1.00, I want real consistency, outside or inside? Thanks, in advance, for your best advice. Paledun