What causes a cap to pop and your gun not to fire? This happened to a friend of mine recently, and it happened to my father before. Personally never happened to me, and I would like to keep it that way.

Usually if you fire a cap but it fails to ignite the main powder charge;

a blocked fire channel. That is why they recommend you pick the nipple between shots.

a poor fitting cap or worn nipple which is not allowing the cap to seat properly. So the first strike sets the cap and the second one fires it.

It could be because you did not clean the breech of all lubes and oils prior to loading. This can sometimes begin to kill the powder charge.

Another cause is when you swab, you're using too much moisture on the patch and getting the fowling wet, pushing it down further into the breech blocking the fire channel. You need to run dry patches after a wet patch to make sure you are drying the barrel and breech as much as possible.

In my traditional rifles I often times will swab with pure alcohol. I find this has caused a decrease in hangfires and misfires for me. I think this is because the alcohol almost drys itself in the barrel. Also wipe the fowling off the nipple from time to time.

Another reason is bad caps. I had a terrible time with Remington #11 caps. I had 10% misfires in one tin alone. My favorite caps are the Dynamite Noble 1075 or the CCI #11 Magnum.

1. Blocked flash channel - Fouling, oil, other dirt/crud in channel/nipple

2. Excessive oil or moisture killed the powder charge or part of it where the flame strikes

1. is more common.....

The boys are right. I had a blocked channel due too to much moisture on a swab. I pushed the fowling down into the breech plug and even if you dry patch after that it doesn't matter as you cannot get to the breech channel. So I swabbed both a wet then a dry, capped, and pop nothing. When that happens the best thing is to wait and keep on aiming because you never know what can happen. Once you have waited, pull out the breech plug and load, (never reuse the load) and inspect it. This is where my breechwas completely blocked. So some slovent and patches it was good to go and fired just fine after that. I make sure to keep a nipple pick or pipe cleaner with me and it does the job fine. I had a hangfire that scared the bitjesus out of me once. The cap went off and I waited, then as I started to unbolt the action BOOM! Luckly no one was hurt and the muzzle was in a safe direction downrange. Preventative cleaning and common sense are two big factors that will prevent any misfires or hangfires and alongwith proper loading techniques should not result in mishaps.

I know the new Remington ML's gave me trouble with 777 pelllets...............had 4 in a row fail, switched to Winchester 209's had no more failures.