Hawke Vantage IR 3-9 x 50 AO Mil Dot.

I came on to ask a similar question. With an AA Q-Tech moderator on my HC I get about a 50mm increase in pellet impact height at 20 yards. There is no other deviation and it is a constant increase.

Is this unusual or normal?

Tin Bum supply the FAC rated spring with their short stroke kit to keep the power at 12 foot pounds, if the spring is the original it will not be stiff enough.

They are a M3 x 3mm and you can get them almost anywhere, when you put them back in you should put a drop of thread-lock on them.