I’m not sure if this is intended behaviour or not, but of the two amps I have, neither will auto-fire despite that option being turned on. This is a bit onerous for a mobile player, since a lot of sections that require amp usage are time-sensitive and generally (understandably) not calibrated to give the kind of leeway touch-control users might need. If this is indeed intended behaviour, I think it would be best to clearly state this before mobile players can invest in crafting their own amps, as this is information that might be quite important to consider when choosing the firing mode of one’s weapon.
Another, related, problem I have encountered is the alt-fire mode: is it anywhere in the settings to make that button a toggle? Since its default position is in the left hand corner, where the movement is (which usually requires near constant input), it’s a bit contrary to expectation to have another button that requires frequent, time-sensitive input on the same hand, particularly considering how popular it is for people to primarily control mobile games with only their thumbs.