Author Topic: .30 cal Pellet Comparison  (Read 505 times)

rsterne

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.30 cal Pellet Comparison
« on: July 14, 2020, 06:51:33 PM »
I had a chance today to use my .30 cal BRod to test some pellets.... It is regulated at 1950 psi, and has a 26" twist TJ's barrel.... It is running an SS Valve that I got from Travis, with a few mods and tweaks that I did.... I tested 6 pellets in the 44-50 gr. range, which is what the gun is tuned for.... In addition, I ran an assortment of pellets and slugs from 59-70 gr. (shown in red).... These are actually a bit heavy for the way the gun is tuned, but I thought we might learn something.... Here are the results, corrected to ICAO conditions....



Note that the velocity stated for the Ballistics Coefficients I measured using my LabRadar is the average velocity over the interval used to calculate it, which was 10-70 yards for most of the ones tested, but only 10-50 yards where the 70 yard data was questionable.... Note that there are a few gaps in the 90 yard data, as the LabRadar failed to reliably record some projectiles past 70 yards in this caliber....

For the pellets under 50 gr., the FPE increases with pellet weight, as expected.... Once again (as per the .35 cal tests), the NOE Hunter pellets had a significant advantage in BC compared to the JSBs, which pleases and surprises me.... Obviously the Meplat on the hemispherical nose is not a disadvantage.... The retained energy at 90 yards is significantly greater than the JSBs, and the accuracy of the light and medium weight Hunters is similar.... The heaviest Hunter tested was showing signs of spiralling past 50 yards, and the group was a lot larger than its lighter cousins.... The Predator Polymags were a disappointment, both in BC (which I expected), and in accuracy.... They painted a pattern 16" wide, and the wind was only about 4-6 mph.... I was mostly interested in the Chrony results, but was paying enough attention that their relative group sizes should be in the ballpark for 10 shot groups from this barrel, at these velocities....

The heavier NOE Magnum pellets were a disappointment.... They all spiralled badly at this velocity, and the heaviest ones were so bad that the LadRadar had trouble tracking the velocity past 50 yards, so that BC was calculated only from 10-50 yards.... The 4 slugs that I tested had a large ES, which makes me question not only the LabRadar results, but the accuracy as well.... I shot them as cast, and the velocities were lower than I expected, which combined with the large ES makes me suspect they need sizing.... The groups were good left to right, but strung vertically quite badly, which would be expected at 100 yards with a large ES.... The slugs need sizing, and both them and the heavier pellets need to be tested in a gun tuned for 120-140 FPE to see how they perform at a higher velocity....

Bob



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