Fri Aug 28, 2020 11:03 am
Revisiting an old thread as as having similar experience:
I bought a s/h but mint Prosport .177 a year ago (with a TbT tuning kit) and it shot (and still does shoot) beautifully. It chrono'd at 10.6 ft.lb, and with the smoothness was ideal for my uses at 25-45 yards.
Having got fully used to it, I can get 1/4" groups at 25 yards and I've only been shooting rifle for a year. Probably 2,000 shots through it.
It is however very hold sensitive. Minor changes in hold result in a similarly tight group (so the 'grip' is right but the hold position affects the gun differently) but a change in POI of say 1/2" max. I'll post separately on this.
Chrono'd it again (not because of above) and noted that it's down at 9.3 ft/lb. This is all with AA Field 8.4gr 4.51 (which measure with Pelletgage to 4.52 at least. Resized to 4.51 to test also - little difference although a tiny bit more consistent.
Stripped it and it is all pretty much spotless, just wiped with grease. Two preload delrin washers on top hat.
So, have ordered new spring. The spring doesn't 'roll' totally concentrically, but it's not what I would call 'bent',
However, seems a bit odd to have lost this much power?
Any other thoughts before it goes back together? thanks