It's snowing today so nothing else to do except set up the chronograph in the basement and make sure the guns are ready for spring. First up is my Daystate Harrier .20 cal which I just recently tuned for lower velocities in the hope of obtaining a little better consistency than I had under full power. As long as I avoid over-charging, it looks pretty good with lubed pellets, around 15 fps variation over 20 shots. It has always tended to produce somewhat erratic velocity swings at higher pressures. Such are the joys of owning a non-regulated PCP.
Next is my TX200HC in .177 caliber. I tried both the JSB 7.87 and 8.44, with the 8.44 being the 4.53 head diameter. The lighter pellets tended to produce some low fliers. I don't know why that would be, maybe variation in head diameter. In any case, the 8.44 grainers in the 4.53 head diameter produced more consistent velocities as well as a little more energy at the muzzle. I will be experimenting with those when the weather breaks to see how they do accuracy wise.
Last is my R9 shooting the JSB 8.44/4.53 pellets which I already knew to provide good accuracy. Velocity variation was a little more than from the TX200, but still around 15 fps for 20 shots.
Both the TX200HC and the R9 had been fitted with Vortek tune kits, The TX200HC with the15 FPE kit, and the R9 with the12 FPE kit.
In case anyone is wondering, using the TX200HC and JSB 8.44 pellets as an example, a 15 fps spread in muzzle velocity translates to a 0.220" variation in POI at 50 yards. Not too bad, but when it doubles to 30 fps as in the case of the JSB 7.87 with the same gun, the vertical spread grows to 0.410", which is starting to look pretty significant.
Next is my TX200HC in .177 caliber. I tried both the JSB 7.87 and 8.44, with the 8.44 being the 4.53 head diameter. The lighter pellets tended to produce some low fliers. I don't know why that would be, maybe variation in head diameter. In any case, the 8.44 grainers in the 4.53 head diameter produced more consistent velocities as well as a little more energy at the muzzle. I will be experimenting with those when the weather breaks to see how they do accuracy wise.
Last is my R9 shooting the JSB 8.44/4.53 pellets which I already knew to provide good accuracy. Velocity variation was a little more than from the TX200, but still around 15 fps for 20 shots.
Both the TX200HC and the R9 had been fitted with Vortek tune kits, The TX200HC with the15 FPE kit, and the R9 with the12 FPE kit.
In case anyone is wondering, using the TX200HC and JSB 8.44 pellets as an example, a 15 fps spread in muzzle velocity translates to a 0.220" variation in POI at 50 yards. Not too bad, but when it doubles to 30 fps as in the case of the JSB 7.87 with the same gun, the vertical spread grows to 0.410", which is starting to look pretty significant.