Thank you. I believe if you could get the 18.13s up to between 840 – 900 that they’d begin to show dominance.
A good compromise tune would be to shoot the 15.89s at 900 fps and the 18.13s at 860 fps.
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Alex, nice shooting! I shoot mine regularly at 50 yards and do get 1/2" groups, but if I shoot 8 five shot groups, my average is probably more in the 1/2" to 3/4" range, and only if wind is minimal.
Derrick, re. your comments above. I have a DS Regal XL .22 caliber (with HUMA) which was tuned last Spring by Scott (Motorhead Tuning) and after the tune, the Regal was shooting the JSB 18.1 at 805 FPS average and JSB 15.89 at around 850 FPS. For whatever reason ( and like Alex mentioned in his post), the velocity has diminished quite a bit and I cannot figure out why. I checked the breech O ring and it is fine, but now my Regal is shooting at 760 FPS with the 18.1 and around 810 FPS with the 15.89.
Gun is not loosing air as far as I can tell, but I am suspicious. Q. Does anyone know if there is any YouTube video that shows how to adjust the Hammer Spring with the Regal? I know it does take time, but I would like to try and turn up the power to about 840-860 FPS for the 18.1 and assume the 15.89 will be close to 900 FPS as Derrick mentioned above. The 15.89 has pretty much always done a bit better with my Regal, but at 760 FPS, it does seem too slow right now.
Thanks, Tom