I use a 17” laptop messenger bag for my S2, bought it off the AAFES military website (I’m retired USAF). I can put my S2 with Holosun 515 Elite on a low mount (am able to co-witness with the CZ irons) and a locked and loaded 20 round mag in the “computer” slot ready for use; and put spare mags and other items in the other large slot. Can also carry smaller items in the front 3 external pockets. I also have a Alienware Computer bag for a 17 inch laptop that will fit all this stuff. That option has more room so I can always use that as a “bug out” bag if I need to. Lots of options out there, just find what suits you and your needs. Good Luck!!