I see what you noted and agree with your assessment. Yes the 18.13s are from a few years ago. So are the 25.4 MRDs. I was mainly looking at general shape comparison, not specifics to THAT particular sample pellet, so I didn't make a big effort to get that first photo in focus. It kinda looks like the 25.4 has a big parting line down the length of it too.....
I noticed the starburst at the bottom of the skirt too. I'm not sure if it'll have any effect on flight. And consistent flight is high on my list of desired traits of a pellet.
From the standpoint of differences in the general shape.....
I see that the skirt is thickest with the 18.13s and gets progressively thinner as the weight goes up, at least for these three sample pellets.
I also find it interesting in how similar the length from base to bearing surface on the head is, across all three. The length is a smidge more from base to head bearing surface on the 25.4, but the other two are very similar in that particular measurement.
I also find this fascinating.....
Obviously pellet designers have certain parameters that they have to live within, in this case .217" diameter pellets, and typical airgun twist rates. So to change weights they're stuck tweaking only a few parameters.
The angle where the skirt and rear-head comes together seems to be a prime area of focus for JSB weight variations, and to a lesser extent, skirt depth. The issue with skirt depth variations is that it shifts center of gravity, often in bad ways.....so for angle of head and skirt....
Look at the variation...
And look what that does to the length of the rear-head (gotta be a better name for it than that...retrograde-head? Inferior lateral head is probably the most accurate)
So, from an aerodynamic perspective (I have zero experience or actual formal knowledge there) from a laymen in those regards.....sure seems to me like there'd be more turbulent air molecules stripping off a LARGER inferior lateral head in flight than a SMALLER inferior lateral head. And to really get into the trash terms.....smaller inferior lateral head seems like it'd be more slippery in flight than a larger inferior lateral head....and now maybe we're talking BC?
So anyways, that, coupled with simply shooting the 18.13 and the 25.4 AND the .20/15.89, and seeing how they compare to each other in the wind has me guessing that the new 20.83 will be an improvement to an 18.13, but not surpass a good 25.4. (and yes, a "good" 25.4 is a whole different can of worms, but they CAN be extremely good when shot from a barrel that likes them).
I suppose I'm mostly interested in seeing if the .22/20.83 can outshoot the .20/15.89. The extra weight would make it a 38-40fpe projectile, instead of a 30fpe projectile like the .20/15.89. If the BC is an equivalent 0.048ish, the extra fpe would be nice for uses like extreme field target where some of the targets in use need to not only be hit in the correct place but hit HARD in the correct place.
Oh to be a fly on the wall of JSB's pellet designing and testing team.....or to be PAiD to be there!!! Dream job.
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