Ah yes, one of the magnificent TKB series of weapons made in Soviet Union, this one is the TKB-011, a bullpup assault rifle designed by Nikolay Mikhailovich Afanasyev, same designer behind the LAD machine gun and OTs-02 Kiparis, and was manufactured by Tula Arms Plant.

Although it was never adopted by the Soviet Military in our timeline, perhaps it's the standard issue of the Soviet Union in an alternative timeline.

SFM version:
https://steamcommunity.com/sharedfiles/filedetails/?id=2758332766

Includes:
sketchfab\newsomellc\skf_newsomellc_tkb_011.mdl
sketchfab\newsomellc\skf_newsomellc_tkb_011_bullet.mdl
sketchfab\newsomellc\skf_newsomellc_tkb_011_magazine.mdl
sketchfab\newsomellc\skf_newsomellc_tkb_011_magazine_2.mdl

Credits :
Nikolay Mikhailovich Afanasyev - Original Designer of TKB-011.
Tula Arms Plant - Original Manufacturer of TKB-011.
Newsome Interactive - Original creator of the model.
NeoLin - Porting to Source.
And PBR Converter by Fennecai ( https://linktr.ee/Fennecai )

Feel free to support the Lambda Group for more addons.👌
https://ko-fi.com/neolin7812
https://www.paypal.com/paypalme/NeoLin7812