The timing devices are sound activated, and if they are set too sensitively they will pick up sounds from the next bay.
And if they aren't sensitive enough, they won't pick up your shots.
Suppressors are great on .22s for your own practice/use, plus they are a ton of fun. At matches where we have to time you----they just do NOT work on .22s.
We even had to make a specific rule about .22s and timers, because there are only so many times we are going to let someone reshoot a string of fire.
Quote from the Introduction to Steel Challenge post pinned to the top of the Shooting Sports forum:
"Additional comment about rimfire rifles:
Remember, the timers are SOUND-activated. Without sufficient sound, they won't activate. The timers need to be sensitive enough to pick up your shots, but not so sensitive that they pick up shots from different bays.
As such, please don't use a suppressor, and don't use sub-sonic ammunition. Standard or high-velocity ammunition only, please.
We've done what we can to make sure the timer picks up your shots. However,
if it doesn't, it'll be a 30-second run. In the match, you'll get three strikes, but
on the third, we'll be giving the max time.
(I suppose that technically, that means you only get two strikes before you are out.)
What that means is that for a particular string, if the timer doesn't pick up your shots, we'll let you re-shoot the string. In the match, we'll let you do this
twice.
On the third time, though, (and every subsequent time) the time will be recorded as 30 seconds (the max time for a stage). That's two passes
per match, not per stage."