I'm not doubting you did it, thats just a phenomenal group for just about any rifle at 300yds, rimfire or centerfire. Thats crazy! I pulled out the handy dandy Balistic Calculator, and did some math just because I am curious. Mostly because, from 0 yards to 150 yards you say there is 10 MOA drop, but from 150-300 yards there is only 8 MOA drop. I used: 70 deg Farenheit, 500ft elevation, and 1020 millibars elevation. 36 grn Maxi Mag HV @ 1280fps and ~.126BC. 1.5" scope height. Zero at 100 yards.
I came up with
10.02 MOA total Drop at 150yds......................
83.15 MOA total drop at 300yds
655 fps at 150yds.................................238fps at 300yds
34 ft/lbs at 150.....................................5ft/lbs at 300
0.49 second flight time at 150..................1.63 flight time at 300
So, that equivalent would be to come up 40 clicks at 150, but it would take
333 clicks up to hold zero at 300 yards!
WOW. I guess you must really know how to shoot

. Considering a 1mph wind change at 3 O'Clock would produce a 5.1 MOA shift, or 21 clicks.
Jerry
EDIT: please don't take this as sarcasm, I was just curious about the data.