Others What are those wheels on scopes?

[Triggernosis]

I'm still fairly inexperienced with airguns and only own one currently, a Daystate Huntsman Revere in .177.
I've noticed lots of folks have some sort of big "wheel" attached to the side of their scopes. What is their function?

 

[Madhatter]

It's for adj the objective. People set it up so when the scope is in focus the numbers they put on the wheel lines up with an indicator. It tells them what the range is to the target. It comes in real handy when competing in field target. The targets aren't set at a set range like at a shooting range. The rifles are limited to 12 fpe or 20 for depending on which class. Normal firearm scopes are usually focused at 100 yards. Most people don't shoot that far with their airguns. Especially springers. That's why scopes for airguns have a adj objective.

 

[Triggernosis]

Gotcha. Thanks for the explanation.