some observation I have made over the last several years:
1) snapping caps drys the barrel as others have said
2) Leaving a ml loaded overnight from one cold setting to warm setting to a cold setting can lead to condensation. i.e. loading in warm house to going out to a cold pickup to the heater blasting to trudging out to a dewey cold morning in the field. Granted it is pretty dry out right now, but I try and reload my gun every morning and unload at the end of each day.
3) some of the earlier model inlines had many different designs leading to multiple challenges with ignition. Some guys have drilled the nipples to get an increased flash hole for better chance of ignition. I use a welding tip cleaner to clean the nipple, and since it is a small scale file, the opening should get slightly larger after each cleaning.
4) I get far fewer miss-fires after trying multiple types of powder to my final and current powder 777 fffg. The 3f does two things: one, since it is smaller granules it fills the breach plug better, and two, it is hotter.
All of these things have helped me reduce my # of miss-fires dramatically.
Best of luck
