The 30s is a Glock-made hybird. It's the G30 Short Frame with a G36 slide. I have one and it's my favourite pistol.
To get any aftermarket parts like a barrel it takes parts for the G36. Frame parts connector and trigger parts use G30 parts. I use it as my every day carry pistol.
It also fits in holsters for the smaller Glocks. I can carry it in holsters for my G19 and also I can use the Blackhawk SERPA holster for the G30s for my G19, that's handy.
Personally I think you got a nice surprise. If you watch any videos from Hickok45 on You Tube he does several in depth vids about the G30s.