Can anyone Identify this weapon?

[gardnerdesign]

Can anyone identify this weapon? i would guess its caliber is between 50mm and 76mm and that it is chinese or russian ?

[ame="http://media.photobucket.com/image/50mm%20rpg/Hawkwood_777/Russian%20weapons/1242755356748.jpg"]50mm rpg image by Hawkwood_777 on Photobucket[/ame]

 

[kato]

Russian DP-64 anti-frogman grenade launcher. Pretty much a 45mm grenade launcher firing depth charges or HE shells.