I think that's your problem right there.
These guns don't run better dry, especially if the rails, bolt, bolt carrier, and hammer haven't been polished. This is a AK OIL the shit out of her, just keep the Oil out of the gas tube/block. I agree some tight tolerance guns like ruger LCP ect need less OIL, but not the mighty Saiga 12.
I bet if you greased the hell out of the rails, and sprayed some Rem oil or CLP on hammer, and where bolt carrier makes contact with hammer, and where bolt makes contact with hammer, you would reduce a hell of a lot of friction which is obviously causing your