O.K., just for giggles (and because I hadn't worked much with this gun since I bought it), I did some light tuning with it this morning. Shot JSB 18.13's through it for the first time. Was making 32 FPE as I had received it. Easily got it up to 34 FPE just working with hammer spring adjuster screw. Recall that my regulator was received by me set at ~125 bar. After any hammer spring adjustment the hammer spring wheel was returned to setting #7 unless otherwise specified in the chart below.
What did I find out?
1) My gun was received in a pretty poor state of tune, based on power and consistency;
2) Just playing with the hammer spring fine tune got me a little more power, and much better consistency.
3) Gun really sucks the air now, giving me just over 2 good magazines (~40 shots) per fill.
4) Now need to start some accuracy testing with the 18.13's on HS=6.
I then recalled that manufacturers normally use the heaviest 'normal' pellet and longest barrel to test their gun's performance. Not the case with barrel length here, as FX actually gives numbers specific to the
Compact model of the WC3. But what about pellet weight? Decided to try some JSB 25.39's, and power (keeping the same 'best' tune reached for the 18.1's) suddenly jumped from 34 FPE to 37 FPE. And with further tuning and upping the reg, maybe I could get that power up further towards the FX specified 40 FPE??? Not going there though since I really don't need max power in this gun.
(EDIT: 5 of the 9 values I saw chrono'ing the 25.39's at HS=7 were the highest velocity seen for that pellet - 817 fps. So if only using the 5 highest values, an argument could be made that the gun is already shooting at 38 FPE, and getting pretty darned close to the FX specification.)
Anyway, here are the numbers I recorded this morning. Groups were 9 shots each so I could get 2 groups per mag. Pellets were un-weighed, unsorted. Chrono is the FX pocket wireless chronograph. Ambient temperatures were in the 65 deg F range. I normally don't fill my guns to max pressure especially for chrono work, so starting gun pressures were ~230-235 bar. Regulator at ~125 bar. I found this to be some fun and interesting stuff!
P.S.: I don't know whether this makes any difference one way or another, but my gun tested above wears the Huggett shroud instead of the OEM FX shroud.
thats pretty interesting info.. but with the increase in hammer spring it seems fps stays roughly the same but es straightens out with a good hard wack on the valve as observed on line 7. how is that tuning on a bell curve??!
