TX 200 power shifts
Can anyone help m,e almost at wits end!? My TX standard length Mk3 in .177 and in a GNIB stock is behaving strangely. It has been short stroked and normally shoots JSB 8.4 gns at 780 ft/sec. However, yesterday at the club and when the temperature rose, the velocity went down to 734ft/sec, with my shots falling low, particularly at the longer ranges.
I kept it overnight and tried again this morning, when th velocity was back to 780ft/sec as normal. I then placed it in the conservatory this afternoon at nearly 30degrees and once more the velocity had reduced to 734ft/sec or 10.2 ft/lbs. After cooling it in the garage for a couple of hours, the velocity was back up to normal!
I would have expected the reverse - the power increasing in the heat as the lubricants became warmer and slower in the cold, as the lubricants cooled. Am I missing something very basic?