Originally Posted by Jeepergeo
I would not use a fired casing as it could lead to being unsure if the gun is/was loaded. Instead, snap caps are fairly inexpensive and would do the job, plus their color makes it clear there is no live round.
I don't have the magazine in the firearm at all, it in the safe beside it and the spent casing is fed by hand. But I don't plan on strictly using that as my snap cap. I just have to find some where around me that sells them for a .22 as I've only seen them for shot guns so far.