Pg-18 Mukha [*Fly*] I think. The PG-22 has a larger diameter tube.
The grenade launcher on the AK looks like a BG-15 maybe ?!?!?
What I learned to call GP-30 *Obuvka*, which is the launcher designition [means *shoe*, and you're using the prototype designation, Russian equivalent of *XM*.
The earlier GP-25 is called Kostyor [*campfire*] The ammo is not interchangable between the two, and looks nothing like the US M79/M203 40mm grenade launcher ammo. GP is abbreviation for Granatomyot Podstvolnyj or under-barrel grenade. The little VOG-25 grenades are neat little gems inside; the VOG-30s are similar but have a longer bullet-shaped nose, maybe for HEDP HEAT effect. 
