Make sure the rear sight is at the lowest setting.
More than once I have found that the rear sight was moved by others who wanted to "see" my rifle.
(I wonder if it is pay back for the times I've messed with their sights.)
"A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed."
Life Member NRA
Life Member NAHC
Former President of the ECPT (Eifel Combat Pistol Team)