A RTB combine soldier? What does it do,and what does it look like in source?

[teamfortress2invasionfan]

So ive been browsing google of half life 2 beta concept art and i came across a RTB combine soldier,but i dont know what it would look like in the actual source engine and what it does. It looks like it would be a early shotgunner
   Since in there hands look like a shotgun.

[teamfortress2invasionfan]

https://www.deviantart.com/freemanbg24/art/RTB-combine-soldier-concept-art-323860160 this is the link i found it from.

[HaRaD]

It's just fanart.slightly only the helmet similar to the helmet from concept art.