I’m not an authority by any means but I think the receiver on the VEPR uses a different receiver than a stamped AK receiver. I think the VEPR uses an RPK receiver which is heavier. The gas piston design and the trigger components are the same basic design. I wonder if the difference is a variation on an AK design is somewhat the same difference as using a forged receiver compared to billet receiver in an AR. Both receiver accomplish the same thing but the appearance is slightly different as is the manufacturing process and weight.
The AKM and stamped AK use a squared off receiver at the point the butt stock attaches. The VEPR needs to be modified to accept a standard AK butt stock because the rear corner of the receiver is different. The VEPR is manufactured to make it easier to import and is more difficult to mount a conventional AK butt stock and pistol grip in a similar fashion as a Saiga AK variant.
The AKM and stamped AK use a squared off receiver at the point the butt stock attaches. The VEPR needs to be modified to accept a standard AK butt stock because the rear corner of the receiver is different. The VEPR is manufactured to make it easier to import and is more difficult to mount a conventional AK butt stock and pistol grip in a similar fashion as a Saiga AK variant.