Shooting .38 Specials in the garage?
To the OP, thank you for asking this question in this forum. I hope you heed the advise of most of the guys, those who said "bad idea".
Many, many years ago, back when I was young, immature, stupid......living on the other side of the world in a country with many gun regulations and little enforcement, well,...'nuff said. 'Round 'bout the same time, I also rode motorcycles at 200-240 kph on narrow, two lane, winding country roads. Consider myself extremely fortunate to still be free and alive.
Please, please abandon this ridiculous idea of discharging firearms in your garage, in a place not designed and completely unsuitable for your intended use and in a populated area. Who knows where that slug may end up?
Think
safe and
responsible firearms ownership. We sometimes call our firearms "toys", but we are not little boys anymore. We have to look beyond the legalities in this issue and always do what is right.
The other side is waiting for someone to do exactly what you are planning, have a mishap, we'll be all over the news, and that's only the beginning.