To check the breech plug, hold the gun(action opened) up to a light/sky and see if there's any light coming through. If there is, your flash hole is clear for firing. If not, get to cleaning.If it is clean start by getting new primers. They're[primers] veryvulnerableto slight moisture in their paper and plastic containers, andbeing stored ina container that doesn't breathe could have been the cause of the problem here.Perhaps you didn't clean the flash hole before stowing it and insufficient flash is getting to the powder. Next, you stored your powder with a funnel cap instead of the factory cap, which is likely to have allowed some moisture in. To see if your powder is burnable, take a very small amount(a smallpenny sized pile)outside on a non-flammable surface and see if a match lights it up. Next time you get primers and powder store them on a shelf where moisture doesn't have a chance of collecting unlike in a plastic container. It's okay to store your other accessories in the same tackle box, though. Hope this helps.