I took out the HW97 and HW98 today. After a teardown I wanted to sight them in, but the indoor ranges were closed. Unfortunately the wind was blowing 16-23 MPH with a few gusts to 26 MPH. I positioned the truck so the wind was at my back and set up on the tailgate with the targets at 12-13 yards.
Both HWs have ARH UK 12lb kits and are 177. I received a couple of short stroke spacers this week from our cousins across the pond at Tinbum Tuning. The 97's piston seal looked burnt so I also switched it out with a new Maccari SGS seal and added a 8mm spacer to the piston.
The 98 has a Vortek piston seal and was tuned with Krytox. The rifle is very smooth operating and shoots well. I added a 10mm spacer to the piston and the shot cycle seems quicker. I no longer use the factory metal sleeve and the spacer helped quiet any residual noise.
ARH recommends using 7.9 grains with the UK kit, but I've had good results with 8.3 to 10 grains. The Norma FT Heavy 9.1 grain pellets shot well in both rifles and the 98 seems to prefer them with both ARH and Vortek PG4 12lb kits. The 97, like my pup Stella is reliable and eats anything.
Overall, I think TBT's delrin short-stroke spacer is a good addition. My 97 in .20 already shoots very well, but I'm interested to see if it would benefit. TBT advises customers there could be a slight drop in velocity with the spacers so I plan to use the chrony to see how they're shooting. I'm also planning to do some accuracy testing further out when the weather is on my side.
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