I used to achieve very tight ES (10 or under) and SD (2-3 or under) with my FX Impact M3. I am now getting ES of 40-50 on my first magazine, then it tightens up to around ES of 15 or so on the second mag. I also used to get short range MOA or sub MOA POI’s. It’s now some MOA but several fliers – short range being 35 to 50 yards. Overall, first magazine is about 2.5 to 3.5 MOA.
Barrel has been cleaned, breech o-ring changed, second regulator is consistent within 2-5 bar, internals cleaned and lightly polished (valve, valve spring, spring guide, valve rod). Pellets are all washed and sorted by weight. The puzzling thing is that it tightens up some after one magazine (25 shots.) Can anyone tell me what I might be overlooking?
Here’s the setup:
Impact M3 standard (600mm) with unmarked power block (s/n 216xxx)
.25 caliber – shooting FX and JSB 33.95 grain pellets – washed and sorted by weight.
Macro 16, Micro +/-3.5, valve about 4, second reg 120 – these are factory specs for this pellet.
First regulator replaced with Saber Tactical first reg bypass.
Standard internals (hammer, spring, etc.)
Average velocity 872 fps when ES is tight - 830 to 900 on first mag now, then it tightens up.
Any help or suggestions will be helpful, especially if you have experienced this same situation.