It means his scope has a mil based reticle (mil dot or MLR) and has 1/10 mil adjustments as opposed to many scopes being mil-dot reticle and 1/4 MOA adjustments. Its the way a mil based scope should be set up. Either mil/mil or moa/moa, as long as they match it doesn't really matter.
John 8:12 "I am the light of the world. Whoever follows me will never walk in darkness, but will have the light of life."
The biggest difference for someone who doesn't actually range with the reticle is a mil turret will move the reticle roughly 1/3" per click at 100yds as opposed to a MOA turret which moves the reticle approximately 1/4" per click at 100yds.
It means his scope has a mil based reticle (mil dot or MLR) and has 1/10 mil adjustments as opposed to many scopes being mil-dot reticle and 1/4 MOA adjustments. Its the way a mil based scope should be set up. Either mil/mil or moa/moa, as long as they match it doesn't really matter.
