a couple of different things you can do.
most find that the TM velocity reducers don't work too well and it would only work in semi auto mode. I'm a little iffy on it's consistency to maintain the lower fps. I for one, wouldn't allow people to play running the velocity reducer.
I know some people run one gun indoors and out and only change their front end to a shorter one which nets them a lower fps safe for indoors. the change in inner barrel length seems to work for some setups.
ultimately, you can swap out to a spring that puts you in the indoor range and just run it outside.