Have you tried placing a few pieces of camera film negative under the scope in the rear scope mount?
In air rifle FT shooting this is a common practice to eliminate scopes that can't zero down enough to shorter ranges, just don't over tighten the scope mount upper ring screws.
Finger tight and a quarter turn is all that is needed.
Just read the link on shimming, don't use card as it will compress, metal strip can corrode over time whereas camera negative does neither of the above plus it's thickness is very consistent.
Yesterday I was shooting my A&K SVD at a tin can at 40+ using .25gr bb's.
The FNG is correct about the cocking bolt, it needs the bolt extension!