Hey, I just tried it.
Well, first of all, if I launch the game via the desktop shortcut, I get an error message on loading and spawn under water.
I launched the game via the main exec and it ran fine.
Visually its okay, albeit a bit bare bones. The weapons room is pretty cool though. You could really increase the brightness because its overall very somber and I think thats a bit distracting from the range firing gimmick you got going. Firing weapons also makes the shadows glitch out (disappear) which is especially distracting when firing silenced weapons.
I appreciate that you added new sounds but they are somehow worse than the default ones these weapons come with. They are mastered a bit odd and stand out. You should replace the crosshairs because I can see a greyscale block around them.
The MP6 weapons seem to be implemented from the vanilla FPSC pack and need some gunspec adjustments. Mainly gunlag because they are just stiffly attached to the camera with no motion feedback when turning around. This is an easy fix.
A bit harder to fix are some sound issues. For example, standing still with the MP5 variants plays the fire sound.
Also with a gun range game, your target audience are fire arm enthusiasts... that means the weapons should behave like their real world counterparts which they don't. For example, swapping a magazine plays a full reload cycle even if there is still a round in the chamber. You can use the advanced weapons dlc or older media by errant AI. Errant AI usually takes great care to make sure his weapons behave like real guns mechanically which is a must have for a gun range game.
I noticed some basic shading on the weapons, but there don't seem to be proper PBR maps that you advertise. The hands have a slight metallic shimmer to them, the guns don't and normalmapping seems to be non existant. So combining and overhauling the shader maps is a must do. Here is a tutorial on some basics if this is new stuff to ya: LINK
I've shown that PBR realism screenshot above to a few other 3d artists and they either thought it was a bad joke or just sad, so... just remove that?
All in all, I think its not that bad, you took your time with some custom content which I applaud but as it stands it seems to be more of an alpha than a finished game. At least to me