Little knob on bottom of scope?

[ginnz]

Hey guys,

I got a question regarding some scopes.... What is the little knob on the bottom/corner of the part where the elevation/windage is? some scopes have this little knurled knob there like my Leatherwood M-1000 ARTII, and I notice the Steiner Predator Xtreme has the same little knob. Its like its to adjust something, but i dont know what, and i dont dare to try and do anything with it.

anyone know?

ginnz.

 

[Fenix.NZ]

some scopes have a sealed recess there filled with a silicone or expoy.. i always assumed that was the port where the scopes are nitrogen/argon/whatever magic gas they use to fill scopes so that they dont fog internally

 

[ginnz]

From a diagram in the leatherwood m-1000 manual, it looks like a support that sits cross corner from the elevation/windage turrets.

 

[Flying_Finn]

I was about to say RTFM (Read That Fine Manual).

 

[wheaty]

Normally there is a purge plug on most high end scopes and you usually see some sealant on the plug itself.
The nitrogen purge will normally last only a short time as nitrogen has a smaller molecule than most gases and it leaks out through the seals. Scopes are normally not pressurized, just purged free flow.

 

[jjohnwm]

That sounds like the posi-lock feature on some Burris scopes. It locked the windage and elevation adjustments in place, and had to be loosened before the scope could be sighted in, then locked afterwards.