Kind of got off on a slight tangent with the squib discussion. Tap and rack is a defensive shooting technique to deal with type I and II malfunctions in a defensive shooting situation. (You probably know this already.)
While a squib would play havoc with this technique, for defensive shooting, quality defensive rounds from a reputable manufacturer would be the recommendation. And defensive shooting guns are likely to be larger center fire caliber, not rim fire. Modern center fire factory ammunition, stored properly, is very unlikely to experience squib loads. And if you are in a firefight, you probably don’t have time to clear a barrel anyway. Given the odds of it occurring, tap and rack and get back into the fight are preferred.
Now tap and rack in .22 practice shooting does not make much sense, as its not necessary, and malfunctions on .22 are more likely.
In 45 years of shooting I have had many misfires, never a hang fire (except black powder), and about 6 squibs on rimfire only - from factory ammunition. I reload but I only shoot my own reloads. I have never had a malfunction with one of my own reloads. I know of many stories of issues with other peoples reloads. I would never use reloads for defensive shooting where ‘tap and rack’ might be used.
Thanks for a good discussion and following the tangent with me. I created a couple of squibs for my own learning, and only then thought of some potential issues. Training uses a lot of rounds and can be an appropriate scenario to use one’s own loads. In directed training one is expected to perform various clearing exercises. That’s where the issue could arise.