There are many possibilities that would cause misfires such as these. :shock: So, I'll start with the most probable.
1. If you reload, make sure that the primer is seated just below flush with the primer pocket. A misfire involving the primer in this way is the primer literally "absorbing" the shock of the firing pin.
2. If you don't reload, check the brand of ammo; generally, I like sticking to domestic brands of ammo if they're affordable and for when I don't feel like reloading.
3. The problem could rely on the most likely cause of a misfire on the gun's part. (BTW, I'm not a gunsmith, I am just sighting the most probable causes in my opinion, but if in doubt, have the gun inspected by a professional gunsmith.) Check the firing pin mechanism, as it could have a weak spring, or something to that nature,
These are just a few things to check out for, but please be sure to have it examined if the problem is with the gun and not the ammo. Hope this helped. Patriot