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google到了这个:
http://www.gatewaytoairguns.com/ ... p?topic=1629.0;wap2
Our research on pellet head sizes has proven to be somewhat entertaining.
What are you actually getting when you buy a tin of pellets claimed to be 4.51, 4.52 or so on.
We bought a tin of JSB Exact (4.53) and a tin of FX Premium (4.52)
Setting the micrometer to the claimed pellet diameter, we simply observed which pellets heads passed through the set gap. We didn’t use the micrometer’s ratchet for fear of deforming the pellet.
Here are the results of our measuring:
JSB Exact (4.53 mm) Sample of 10 pellets.
Set at 4.53 all 10 were smaller.
Set at 4.52; 9 were smaller.
Set at 4.51; 6 were smaller.
Set at 4.50; 3 were still smaller.
FX Premium (4.52 mm) Sample of 10 pellets.
Set at 4.52 all 10 were smaller.
Set at 4.51; 9 were smaller.
Set at 4.50; 3 were smaller.
也就是说虽然标称到4.52,但大多数还没有到标称直径
反过来还有人做过实验,测试不同直径对应的精度:
daved:
Hey, Johan,
Nice write up, and some nice research there. So now that I've been nice, I'm gonna disagree with you :-). Actually, the only thing I take exception to is your PS regarding chrony results. Awhile back, I ordered a mixed sleeve of JSB Exacts, head diameters from 4.50 to 4.53. With a freshly tuned Gamo CFX and a brand new Chrony Beta, I proceeded to test both velocity and accuracy. The one thing I don't have is a scale, so I can't weigh my pellets. But JSB's have a history for being very consistent in that regard. So with the assumption that the weights were as advertised, I found significant differences in both velocity and accuracy, with that gun. For whatever reason, the 4.52 was the best in all categories, accuracy, velocity, and deviation. 4.53 were slightly slower, the 4.50 and 4.51 were MUCH slower, and accuracy was, well, shotgun pattern rather than groups. Don't have the data in front of me, but as I recall, the 4.52's averaged around 860 fps, with maybe a 5 fps extreme spread. The 4.50's dropped over 100 fps, and like I already said, forget hitting what you were shooting at.
Interesting current note. The gun used above has recently been converted to a gas ram. And now it flings 4.52 Exacts all over the place. The 4.50 JSB Match Diabolo S100 is my current control, on my 10 yard indoor range, that pellet will consistently group 5 shots inside a 1/4" bull. The Exact 4.52 used to be almost as good, now it opens up to almost an inch at 10 yards! The really weird thing is that the 4.51 and 4.53 now group slightly over 1/4". Haven't tried the 4.50's yet. Nor have I chronied any of them recently, but will be soon. Just thought I pass along my experience.
Dave
似乎直径更大的初速更大,或许因为封闭更紧密?
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