re: Rimfire ammo question

29 degrees isn't extreme as far ammo goes -- rimfire or centerfire.

However, if your gun has a lot of fouling (not the bore -- talking about a dirty gun with oil that has old powder in suspension), and//or you are using grease or oil that gets noticeably thicker at low temps, that could contribute. Any congealed oil that could affect the velocity of a striker (or hammer) would seems to be a more likely cause of failure-to-fire than "cold ammo."

Rimfires guns get pretty dirty anyway. Using too much oil, and having that oil mix with burnt & unburned powder, could easily cause failures-to-fire.

Also, don't ignore the fact that rimfire ammo (as a group) is less reliable than centerfire ammo, irrespective of temperature.