Help! I cannot find an ATF ruling on an electric trigger.

I'm wondering about a .22 bull-pup project that I would like to try.

There is almost no room in the design for a transfer bar or cable set-up to operate the trigger, and I really do not want to make anymore room.

What might the ruling be if I were to use an electrically-switched trigger, 123C battery and a small electric solenoid? I would have enough room for something like that.

I KNOW that disabled shooters are allowed to use electric triggers and air-powered set-ups...But I need to know the legality concerning non-challenged folks.

The only reason that I'm really concerned is that an electric trigger could (in my opinion) be easily set-up as an electronic trigger, capable of pulsing the current...which would put the project in NFA territory, and I don't want to go there.