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Speed Deviation: JSB King Heavy 33.95gr pellet vs NS 26.8gr slug

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Powerbroker

Powerbroker

Member
Jul 27, 2019
271
2
Metro Manila~Quezon City, Philippines
There seems to be a huge difference in sped deviation between the two. I have shot 4 strings for both the slug and the pellets without changing power wheel (No.5) and reg pressure (125bar).

Given: FX Impact, PP with 57mm spring, 600mm slug barrel, 125bar reg pre., wheel at 5, FX chrono and 4 strings shots for both pellets and slugs. No lubing. straight from the box.

Nielsen 26.8gr; speed dev is between 1.1 to 1.7. Ave speed: 966 

JSB 33.9gr; speed dev is between 2. to 4. Ave speed: 901

Is this the real score for anyone?

1588301905_19069889285eab905153ee53.46622721.jpeg



 
The difference may lie with the ammo or with the gun's state of tune. There's a big enough weight difference in the two that they'll spend differing amounts of time in the barrel, which means the amount of hammer spring tension that is optimal for one may not be optimal for the other, and that will affect the SD and ES.

Try dialing it in to 97% of peak velocity for each and see how they fare. 
 
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Looks normal to me, are you thinking they should be similar? Because 7 grn in this game is a lot, the kings 25 grn and the 26 nsa’s are way closer obviously speed wise, usually the heavy’s and kings are around 100 FPS apart in most of mine as a gage. Slugs usually a little more surface area=slower, keep in mind the 26 nsa’s are .249, LW barrels seem to like them more than slug liners in my experience? The 33.5’s and up are .250 and seem better from Fx slug liners for me anyway? Hope that helps? If by chance you ment std dev? Both would be plenty good for me!
 
Upvote 0
The difference may lie with the ammo or with the gun's state of tune. There's a big enough weight difference in the two that they'll spend differing amounts of time in the barrel, which means the amount of hammer spring tension that is optimal for one may not be optimal for the other, and that will affect the SD and ES.

Try dialing it in to 97% of peak velocity for each and see how they fare.
Click to expand...

Thank you. I will try and get back.
 
Upvote 0
Looks normal to me, are you thinking they should be similar? Because 7 grn in this game is a lot, the kings 25 grn and the 26 nsa’s are way closer obviously speed wise, usually the heavy’s and kings are around 100 FPS apart in most of mine as a gage. Slugs usually a little more surface area=slower, keep in mind the 26 nsa’s are .249, LW barrels seem to like them more than slug liners in my experience? The 33.5’s and up are .250 and seem better from Fx slug liners for me anyway? Hope that helps? If by chance you ment std dev? Both would be plenty good for me!
Click to expand...

Yes, std dev. I made a little confusion on the average speed. I need to edit. 
 
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