I posted this on the handguns forum, but didn't have much luck, so I thought I would bring it over here and get a few more opinions.

I have heard this is a no-no. Why? I have tried it before (very little, maybe 12 rounds) and have had no adverse reactions)gun didn't blow up).  I looked at the casings and they appeared normal, so why aren't I suppose to do this. Thoughts?

Quoted: The brass for the .22 magnum is slightly larger in diameter than a .22lr. When firing, the .22lr brass expands to fit the chamber, then the bullet starts its journey. Just get a .22lr cylinder from Ruger or Numrich or whoever, and shoot it properly. My $.02

I have the LR cylinder too and use it mostly, but would like to shoot some lr's through the mag if that is all I have with me.  So is it mainly an accuracy thing and not really a safety issue?

I had an old 3 screw single six that came with a magnum cylinder.  I bought it thinking it was a .22lr and was surprised to find about 20% of my cases were splitting.  I took it to a gunsmith who told me it was a mag cylinder and that was to be expected when a dumbass like me shoots .22lr's through it.  In the case of my older Ruger it could have been a safety issue.  I don't think the little LR can cause any catastrophic failures but it could possibly cause some damage?  Anyhow I relegated it to magnums.  They're pretty cheap anyhow, granted not as cheap as LR's pretty cheap nonetheless.