I have just fitted a set of Anschutz air rifle dioptres to a project rifle (11mm scope rail) I am using for Bell Target.However the rifle is shooting exactly 4 inches low at 6yds.

I need a set of risers for the rearsight but what size and type ?

I have been looking at Intershoot SE Boost risers at 12.5mm rise but they offer 2 options for Anschutz

Do I need the Anschutz 1913 type/

OR

the Anschutz 1813 or Earlier type?