There is the notion of AR saturation impeding gains after a certain dosage… But 300 v 600mg certainly isn’t going to induce saturation at either dose. Within skeletal muscle AAS upregulate and induce the synthesis of new AR. you’d have to take a dose big enough to cancel out the effect of new AR synthesis, inducing a state of super-saturation thus a higher dose wouldn’t equate to more gains
If @trt_phoenix was right about 300mg giving identical gains to 600mg/higher dosages… Than all on the Mr Olympia could’ve gotten there on 300mg test weekly, some GH and insulin… That simply isn’t the case
In the past I’ve linked 1-2 studies that show gains in fat free mass increase within a dose dependent fashion (in which total body water in ratio to fat free mass IS taken into account)… The results still indicate a higher dose = far greater gains… but also more sides (haematological alterations become more apparent, bigger hit to cholesterol etc). For one to say perhaps the gains accrued from higher dosages are partially derived from glycogen, electrolyte retention etc… this would be a correct assumption, and this has been demonstrated within a study of athletes using 100mg dbol/day for 6 wks. To assume ALL gains past the arbitrary dosage of 300mg (above what 300mg alone would give you) are acute, glycogen mediated would be a false and unscientific statement to make.
One has NO evidence to suggest the saturation dose is 300mg, thus one would have not reason to believe all gains made past 300mg stem from water, glycogen and electrolyte retention.