Why IMHO JSB 25.39gr is better than 34gr MKII out to 100 Yards

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davidsng

davidsng

Member
Jul 11, 2017
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Rochester, MN, United States
I'm glad AGN stopped negative accuracy. I'm not trying to bash your guy's favorite ammo. The both shoot great, but MK2 have one flaw I dont like at my gun current speeds. 825.fps mk2 and 930fps for 25gr Exacts. Here the info in video.



https://youtu.be/XbflpXzr054

Note: I have cold weather here in MN. This increased the likely-hood of low shots with the ammo also.
 
Did you adjust the gun to shoot the 33.95g pellets at their optimum speed as determined by the gun? Then the scope? (chrony/target) Compared to the 25g. There is a big enough difference in weight between the 25g and the 34g that I woukd not would assume both to shoot well from the same gun with the same settings. Of course trajectory/poi is going to be different and (if I heard you right) the slower than 'normal' speed on the heavier pellets(790) is going to exaggerate any 'errors'. 

Seems like your gun as it is, is better set up for the 25g pellets. Nothing wrong with that, use them!. But with the right speed for the 33.95's..... you might find different results Or maybe not. 

Just find it tough (again if I got it right, its noisy) to think about a 33.95 at 790fps when all my .25s like them at 890-900fps give or take.


 
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Yea, this is NoT the adjustable gun. I dont have the option to speed up the heavy ones I probably would, if I could.

I really thought 825-835fps (in room temp, I was in 22 degree f weather for 790fps) was going to be okay for pigeon. But with and taking pellets straight from the tin, the variation in weights cause the the vertical shift to be magnified at slower speeds (more arch in the trajectory). Then on top of that, the cold weather and inaccuracy with my cheap range finder, caused some lower shots.

Matt Dubber once said he would take a 1.5moa gun at fast speeds, over a slow 1moa with a loppy trajectory for hunting.

I under stand that now.
 
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Hi Dave, Don't know if this will help or not but there is a guy on YouTube named Gregor Kamensek who has his own channel and has done quite a bit of work with the Priest in all it's configurations including accuracy work with the .25 cal using the 25.4, 34 MK2 and the 34Mk1. Might want to flip over there and check out what he is doing. In general, I would say the Mk 1 can shoot quite a bit faster (around 890 fps) than the MK2 (around 830 to 850 fps) and maintain stability and the 25.4 grain can be shot pretty accurately between 925 and 950 and still stay stable as testified by my Edgun R5M. Your mileage may vary. Also he does something of a detailed breakdown of the gun and explains what has been improved and how everything fits together. His English is pretty good so you shouldn't have too much trouble understanding what he says.

Hope this helps

Shalom

John
 
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