My .22 HW45 was purchased in June 2002. The first mainspring gave 5.7 to 6.0 FPE for quite some time. The second mainspring started at 5.8 FPE. The second mainspring is now down to 5.4 FPE but it's starting to fatigue. I think it has around 6000 shots on this spring.

My .22 HW45 does have the small pentagon with the "F" inside. I have tested velocity on 3 different chronographs... Chrony, Combro, SpeedTach.

My HW45 seems to function best with a very slight amount of controlled dieseling. Velocity is consistent and accuracy is very good. There is no "bang" sound and the smoke at the muzzle is very faint and very minimal.

HW45 details http://my.tbaytel.net/~coopers@tbaytel.net/HW45Review/

Pic showing small pentagon with "F"
http://i36.photobucket.com/albums/e2/airpics7/HW45a.jpg

Cheers,
Todd