Picked up some 30-06 brass which is mixed head stamp, in with the LC brass is some SL brass both year 54 and 56. I ran one of the SL pieces through the sizing die which took some effort, halfway through the die I pulled the case out of the die and noticed that I was increasing the case mouth size by a lot. Found another SL case and the fired case mouth inside diameter is .286 instead of around .310 like it should be. Brass sure looks like 30-06 but the case mouth sure isnt, anyone know what the deal is? Brass is once fired with Mil primer and crimp.