I spent 6 hours with my MROD .22 and my crony yesterday…

…but a few weeks prior I ran a test to see how it performed from the factory and this is the string it produced in stock form:

Crosman premiers 14.3gr 2600 psi sp
846
856
859
863
869
875
877
882
879
883
886
888
890
891
892
893
880
891
895
891
888
893
890
889
885
885
882
879
884
877
871
871
870
864
866
865
858
857

Now that’s not too shabby for a 40 shot string, and shots 6 through 36 procuced a nice 30 shot string with an ES of 20 with a high fpe of 25.5

If I had any sense, I would have simply left this rifle alone and set myself to the task of working on the barrel for accuracy…but I’ve never been accused of having much sense, so I could not leave “well enough” alone!

I have always been an “energy” junkie when it comes to pcp’s…so I had to see what kind of power I could get out of this thing.

I started out by maxing out the hammer spring preload, opening the TP screw wide open, and the longest valve stroke setting.

I shot a string this way, and it very loud (even with the shroud) due to the TP metering screw being “wide open”. I’m not going to tire my fingers and list all of the six hundred or so pellets I shot through the crony, but I will say that after each string I walked the valve stroke in a 1/2 turn and the difference in fps and ES from 1/2 turn in on the valve stroke to 2.5 turns in on valve stroke were for all intents and purposes negligible, that is the ES only varied slightly, the fps hardly differed and the bell curve climb rate was pretty much the same. One thing that did affect the velocity significantly was when I turned in the metering screw on the TP. All the way in made the rifle very quiet, but it also cut my fps down by an average of 50.

All my strings were shot with a fill pressure of 2700 to 2800 psi.

The best power I was able to achieve through the night was with the following setting:

Hammer spring preload on MAX, valve stroke 3/4 turn in from MAX, TP metering screw 1 turn in from wide open. This string was shot with jsb Jumbo RS 13.43 gr as I ran out of Crosman’s by 1:00 am. I figured they travel around 15 to 18 fps faster than the 14.3 premiers.

SP 2700 EP 1900
966
962
967
969
964
982
987
979
982
977
988
989
986
984
983
983
975
982
978
977
980
972
966
958
962
958
955
948
947
942
That gave me a high of 29.176 fpe (nearly four pounds higher than the factory setting) A ES of 47 over the entire string, but a respectable ES over the “meat” of the curve {20 shots} of 31, and a 15 shot ES of 21 as long as I’m disecting the curve, lol.

Depending on what pellet this barrel likes best (so far it is the 14.3 premiers and 14.3 beeman FT, it hates the JSB’s), I will decide if I want to keep it where it is now, or go back to the lower fps and higher shot count…

I can’t help but wonder what a slightly heavier hammer would do for helping me get into the “meat of the curve” faster…, or perhaps a stiffer hammer spring….????

Honestly, this is time consuming, tedious work, and my hat goes off to the professional tuners who offer us their services. I’d rather spend my time plinking and sighting in scopes…

EDIT: Next time I will play around with a lower fill pressure (2600) and see what I come up with. This would be ideal as it would save on air in the long run anyway.

I hope others will post their numbers on their MRODS as I think I am the first. I search high and low and I have yet to find any “numbers” by anyone…, not even by the Man himself. I looked on his sight, but I can’t find any. I would like to see what Mr. Davis and others have achieved so I have something to aspire towards…Until next time….Oh, and thanks for all your help David!

80 Grit