JSB .25 caliber 25.39 grain versus MkII 33.95 grain

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Widget23

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Dec 4, 2016
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TX, United States
JSB Match Diabolo Exact King .25 Cal, 25.39 Grains, Domed
vs
JSB Match Diabolo Exact King MKII Heavy .25 Cal, 33.95 Grains, Domed
PCP: FX Royale 500 .25 (same settings used for both pellets; POI is not the same though)

Has anyone done any comparisons between these? I am wondering about down range (50-75 yds) energy and not so much muzzle energy, but that would be a good place to start if someone has chronographed them. Just from non-scientific observations, it looks like the Heavy MkII isn't hitting as hard as the 25.39. But it looks like the MkII is consistently more accurate. Any thoughts, ideas, places to look for more info? I'm just getting started with the MkII Heavy, so I am trying to gather as much info on them that I can.
 
Lets say it's pushing 40fpe 25.4 is at 842fps and 34 is at 727fps. That's a difference of 115fps which is huge and would make sense why it doesn't sound like it's hitting harder. I wouldn't even think of shooting the 34gr pellets unless my gun could push them in the 850fps range which is 55fpe otherwise your trajectory will be alot more loopy. The difference between both pellets shooting at 850fps is 15fpe which is a big difference. Do you hunt with the gun? Or more going for a long range target shooter?
 
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On one of the calculators for wound depth if you load 880fps then add the pellet weights, it's stated a little better than 9 inches for the 33.95 and 6.7 inches for the 25.39. If you switch to 18.1 and .22 you get a little better than 6 inches. I'm shooting in the high 50 FPE, shooting at 73 yards and 18 power with a 6.5X20 Hawke blasting 1inch Christmas balls I can put my point of aim at the top of the ball with the 33.95's, and at the bottom with the 25.3's Surprisingly at near 1000FPS I'm connecting regularly when I eliminate human error. I do believe the 33.95's at 880 FPS is the optimum set up. Ted won the benchrest with a similar tune.
 
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"Dairyboy"Do you hunt with the gun? Or more going for a long range target shooter?

Click to expand...
Yes, to both of those. Today I was just target shooting at 72 yards. I have a heavy aluminum plate I use to test at long range before moving to smaller targets. With the 25.39 grain the dent in the plate seemed substantially deeper than the dent with the MkII 33.95. "Seemed" as in I'm not out there with a depth gauge measuring the holes - it's just an observation. And I realize that difference could be any number of factors - like pellet construction - and not just a velocity/energy issue. But the beauty here is I can stack 3 of the MkII 33.95 pellets in the same dimple in the aluminum plate, consecutively.

Keep the info coming - thanks.
 
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In my experience while a lot of people swear by the MK 1 & the MK 2, at 100-150 yards, I’ve always found the 25 grain to be more accurate. I know the BC of the MK 2 is higher and blah blah.



But real time experience through multiple air guns has taught me that the 25 grains tuned to shoot between 880/950 almost always beats the socks out of the MK 2’s. I find that the MK2’s sometimes get more impacted by the wind and a draft can push the MK 2 more towards the right or left as compared to the 25 grainers. Guess it’s got to do with the fact that the MK2 has more mass. 
 
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