Is this efficient?

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2D1C

2D1C

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Dec 27, 2016
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.25 crown. 34.3 plus JSB's

250 down to 150bar Reg at 150. pwr wheel 2 TP 22/177

48 shots 897 fps av.

7.67 sd

26fps sd (don't like that) These numbers are using my junk ammo as shown above, all are over 34.3 gn.

Please note guys. This gun is NOT stock. It has been tuned by Mr. Rowe, including the addition of a heavier hammer. pwr lever 4 is now my max. I had this done so I could shoot the heavier slugs when that liner comes out as well as adding a .30 call barrel with a slug liner later.

Dennis
 
.25 crown. 34.3 plus JSB's

250 down to 150bar Reg at 150. pwr wheel 2 TP 22/177

48 shots 897 fps av.

7.67 sd

26fps sd (don't like that) These numbers are using my junk ammo as shown above, all are over 34.3 gn.

Please note guys. This gun is NOT stock. It has been tuned by Mr. Rowe, including the addition of a heavier hammer. pwr lever 4 is now my max. I had this done so I could shoot the heavier slugs when that liner comes out as well as adding a .30 call barrel with a slug liner later.

Dennis
Click to expand...

26 fps spread will be improved if you sort pellets. I think it's a pretty good shot string.
 
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Sorry to say but if that is the stock 480 CC tank, that is INCREDIBLY inefficient for a 23.5" barrel @ 60 fpe in 25 cal... .0995 FPE/CI...** edit .995 not sure why I put the 0



I would suspect hammer bounce or over dwelling the valve if you're at plateau. I'd open up the tp to .25 or max, and reduce the power level IDEALLY through power wheel or lighter hammer...



It is however as you said set up for 30 cal and slug where as you're shooting a .25 cal with pellets so...



You should be getting 30-50% more shots...toss in the 30 cal liner and some heavy slugs and this tune might be perfect...


 
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Sorry to say but if that is the stock 480 CC tank, that is INCREDIBLY inefficient for a 23.5" barrel @ 60 fpe in 25 cal... .0995 FPE/CI...



I would suspect hammer bounce or over dwelling the valve if you're at plateau. I'd open up the tp to .25 or max, and reduce the power level IDEALLY through power wheel or lighter hammer...



It is however as you said set up for 30 cal and slug where as you're shooting a .25 cal with pellets so...



You should be getting 30-50% more shots...toss in the 30 cal liner and some heavy slugs and this tune might be perfect...

Click to expand...


Matt - I think you missed a decimal place. It's .995 fpe/cuin (essentially 1) which for a gun that is being pushed is not really that bad. If Ernest tuned it I would guess he over sprung it to compensate for regulator creep. In some of his earlier videos I noticed that he would tune that way.
 
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I appreciate the comments and suggestions. Obviously I can make changes and I continue to chrony different settings to see if I can find that "harmony"

It was interesting that when the gun was returned Ernest said leave the reg pressure and HST, alone use the TP and power wheel to make adjustments. I have been shooting this set up along with a version I'll put up later with a SD of 2 something and an Spread of 6 something, 842fps. This is much better but isn't any more accurate than the one here. I am going to see how many shots it produces.



Thanx again



Dennis
 
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A tune setup for 30 cal + slugs certainly won't be most ideal/efficient on .25 cal + pellets as I stated earlier. For that you'd have to reduce hammer weight/spring a tad and open up the TP to .25/.30...the way you're doing it now (tp set to .22 / pw 2) currently without having to go over the entire tune is just fine IMO since its arranged to shoot 30 cal + heavier ammo. I'd be curious how the rifle performs currently @ pw 1 and tp .25/30...the tp setting is the worse way to restrict out of all options available and should be left on its appropriate caliber, IMO, unless absolutely necessary to obtain the reduced power you desire.



That reg pressure setting is also set up for 30 cal which is why I am sure he said to leave it be...its a good pressure for that caliber.



I wouldn't pout about 1 fpe/ci that you're currently at. Should be 10-15% higher at minimum IMO but thats entirely related to how its tuned! I bet just changing to slugs alone even in .25 cal (60gr~) would boost your numbers by 10% alone due to the amount of valve dwell.


To put in perspective, a gun tuned to a caliber/pellet weight higher than what you're currently shooting will be much less efficient than when used as it was meant to be tuned, while a gun tuned to a caliber/pellet weight much lower will generally gain efficiency when moving UP caliber/pellet weight, of course you'd be shooting at detuned speeds/fpe but air usage would be incredibly efficient. Hope that helps!
 
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Put the following in EXCEL. These are approximations of your rifles specs and the expected power output. Not sure of port sizes estimates were made.



= ROUNDDOWN(SQRT((ROUNDDOWN((ROUNDDOWN((0.25^2 * 3.14159/4) * 2175 * (23.5 / 12) / 2 * 0.175/0.25,2)))*450240)*0.85/33.95)) = 907 FPS

The above are roughly YOUR rifles settings, of course I am just guessing but the idea was to get the same FPS you get currently...the next I will change to 30 cal...

= ROUNDDOWN(SQRT((ROUNDDOWN(((44.75*2)+ROUNDDOWN((0.3^2 * 3.14159/4) * 2175 * (23.5 / 12) / 2 * 0.17/0.3,2))/2)*450240)*0.9/44.75)) = 887 FPS



So just by changing caliber from .25 to 30 cal, and pellet weight from 33.95 to 44.75, you go from 62~ fpe to nearly 78 FPE...didn't even change the port size! The efficiency assuming you'd use the same amount of air since port stays the same would go up to 1.2 fpe/ci. The stock .30 Crown supposedly does 40 shots @ 82 fpe / 1.1 fpe which your set up APPEARS to be on track to be equal to or greater than.



These numbers are approximations since I don't know all your port sizes and they are very critical to being accurate here.
 
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I wanna see what it does at pw1 tp3! lol. If I understand the FX tuning basics, Power wheel adjusts hammer spring compression..therefore you'd likely reduce power going from 2 to 1, thus reducing air mass ejected due to less lift, but then by opening the tp up to its proper caliber (.25) you'd get increase air mass to the pellet over a shorter period of time due to less choked flow..



It all depends on the rate of compression between power wheel adjustments BUT I suspect a slight loss of power at tp = .25 and pw = 1 but a sizable gain in efficiency. JMO :)
 
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View attachment 1539312154_19937742835bc00a1adf51f2.94081215_Saved Chrono Group - 10-01-2018 05_36_03 PM.eml

Hope this loads
 
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Seems like that is a good spot for the 25 grain pellets IMO! Thats a huge difference between power wheel 1 and 2 if I'm not mistaken? Does your current power wheel have much of a useful range? Does it max out way before hitting 10? If so that may be due to a heavy spring or hammer weight set for the 30 cal which is what I suspect is going on.
 
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Once you get around to getting a 30 cal with proper pellet weight set up, verify you have more usable range than 1-4 on the PW...if NOT than hammer = too heavy OR spring = slightly too high rated. JMO...I'd want full range use of my PW but to each their own!



A more usable 1-10 range would make adjustments finer tuned where FPS would go up by say 25-50 per setting giving 250-500 FPS usable range..opposed to 100~ fps per setting giving the similar usable range of FPS yet less finer tuned adjustments on PW. Again JMO! The above very well may apply once you put the 30 cal on.
 
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