You might give these gentlemen a call but see the note below from the folks at 6mmBR.com:
Scope Boosting and/or Reticle Modifications
Bill Ackerman
Optical Services Co.
(505) 589-3833
oscscope@aol.com
Reticle Swaps. Boost on fixed-power scopes only. Call for model availability.
Wally Seibert
22720 S.E.56th.St.
Issaquah, WA 98029
(425) 392-3567
Reticle Swaps and boosting on certain scopes. Call for model availability.
Cecil Tucker
1567 North Jude Ave.
Odessa, TX 79763
(432) 530-2919
tuckergunsmith@aol.com
Reticle Swaps and Tucker spring modification.
Note: TARGET SCOPES from 6mmBR.com
Exit Pupil: Given objectives (front lens elements) of equal size, the more magnification the scope, the smaller the exit pupil. Remember that the exit pupil, a tiny circle of light, must deliver ALL the optical data your eye receives. Bigger is better by far.
Too small an exit pupil will make a good scope dim and hard to use.
That's why we advise against boosting the Weaver T-36 or the 36X Sightron.
With their respective 40mm and 42mm objectives, the exit pupil becomes too small when they are boosted beyond 36x.