I have one and don't seem to be able to find a schematic for my .177. Did you use a schematic in your dismantling? I am trying to identify the regulator. Mine says it's a regulated version but I can't find a way of adjusting it.
You don't have a regulator on it that's why. And it's not worth the air loss to put one on it. Adjust your hammer spring and it's a pretty good air rifle. Just gotta find the right pellets.
i had the beeman underlever i refunded it and got a jts airacuda the Beeman was a real nice gun but spending some extra money was a better choice for me