After resizing, I found some cases hold the bullet nice and firmly while others let the bullet fall into the case. All were manufactured by the same manufacturer, appeared once fired and identical in dimensions. This occurs with or without the expander being utilized. The cartridges are being used in a single shot, and as I don't have a crimp die, I do not have the ability to crimp. Couldn't anyway, as the bullet falls into the case. Why does this happen? Would annealing the necks prior to sizing correct the problem, or make it worse? The cartridge is an improved 25-20 Winchester. As dies are not available, I've been using a Herter's Universal neck sizing die which works well on most cases while others don't resize adequately. I have a very limited supply of 25-20 cases so I'm hesitant to try anything which will ruin the brass I have. Thanks, Dan