Reply To: Optimal Velocity for JSB .177 16gr out of LW Polygonal barrel
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AA, I want to use the 16 g pellets for 50 Metere shooting. Just figuring the heavier weight will buck the wind better. The 880 fps is what Percula posted in shooting them out of his Thomas. Also, from reading posts, it seems like the cylindrical pellets have better accuracy with a higher fps.
Today I turned up the power adjuster on my TM 1000. The 13 g’s were shooting at 770 fps the way the gun came. This is with the hammer spring adjustment right in the middle. I got it up to 815 – 820 (45 – 50 fps increase) before the ES and SD started to increase. So, I’m thinking, if I can’t have the rifle retrofitted with a power adjuster, I’ll just do one increase on the regulator to get the 13 g’s up to 870 fps with the hammer spring set in the middle. Then I can turn down the hammer spring 45 – 50 fps to get it back down to 820 fps (just under 20 fpe for field target), or I can crank it up the other direction 45 – 50 fps to get it shooting them at 915-920 fps. The 16 g’s shoot 70 fps slower in my rifle, so that would put them at 845-850 fps. That might be fast enough for optimal accuracy. And as Percula said, I’ll need to experiment with the various FPS to see where my rifle shoots them the best.
Just trying to have one gun that will be optimal for 25M, 50M and field target shooting. I will report what Martin has to say.