Got my Crown Power kit- very disappointed

[ackuric]

jking. Here are my calculations for the following real world tests you ran at several pressures.



.25 cal 33.95 gr 500mm barrel / stock ports for FX

59.3 FPE / 886 FPS @ 150 bar (150 bar on the mark)

65.1 / 929 FPS @ 165 bar (A Tad over 160..)

71.6 FPE / 974 FPS @ 200 bar (your reg reading was definitely off here and likely NOT 190 bar...jmo though)


Same shot taken with a Eunjin @ 43 gr

80 FPE / 915 FPS @ 200 bar

The .25s are 600mm

Oops, mistake, just woke up...and those numbers are were with the power kit/vs installed. So its basically the same as running a 600mm with no power kit, I could re-run the numbers with no power kit + 600mm barrel but they'll be basically identical (just checked) so for all intended purposes they still reflect what the 43 gr's should do at that 2900 psi / 200 bar


*edit*

For giggles here are the 600mm numbers

.25 cal 33.95 gr 600mm barrel

60.2 FPE / 893 FPS @ 150 bar (150 bar on the mark) 

65.1 / 929 FPS @ 165 bar (A Tad over 160..) (didn't change) 

72.5 FPE / 980 FPS @ 200 bar (your reg reading was definitely off here and likely NOT 190 bar...jmo though)

Same shot taken with a Eunjin @ 43 gr

81.8 FPE / 920 FPS @ 200 bar

 

[jking]

I had to chime in here..

I have had the mods done..

Its damned simple..

Once intstalled..Power knob was set at max by putting knob in place by hand and adjusting setscrew until you have a couple of thousands clearence on the high side of the cam of the Power knob.. Done..

With the Regulator also modified, you now adjust that pressure and ignore that gauge for up and down pressure changes.. Adjust for speed..

Using the Power knob to fine tune..

Now I shoot my .25 Crown using those 34gr. Mk2s. and they are deadly acurate at 950fps. Setup all at max and adjusted by regulator while ignoring the regulator gauge..

Shooting the JSB 25.4gr. Pellets? I set things this way... Set my cal knob to .177/.22... Power knob set to one or two.. Now adjust Regulator to speed..Fine tune using power knob. These Pellets get unstable when pushed to hard or to fast.. I like them at

840fps..

Please feel free to add more if anyone has more...

Dreamsmoker, what did your gauge indicate at your velocity of 950? Just curious if it was anywhere close to what I came up with during my test.

jk

 

[ackuric]

With the power kit, Dreamsmoker likely hit 950 fps with 160~ bar. 

 

[stoti]

So, just a little follow up. A few days ago I adjusted my regulator to 147 BAR and maxed out my hammer spring and then backed it off about a quarter turn. Haven't been able to shoot because I've been building a bench, it's been raining plus the holidays. So today I finally got to shoot a lot. I ran some shot strings at 40yds. with both the JSB MkII and MkI with the MkI shooting more accurately. My average velocity over all of my shot strings was 876fps using the MkI's. From there, I moved to my 50 yard target to do some accuracy testing with the new settings. I shot my first ten shot group at 50 yards, it was .50", with the first 9 shots measuring .360" center to center. If I wouldn't have pulled the last shot it would have been a beautiful 10 shot, .360" group. I'm not even going to mess with any settings anymore until my Power tune kit gets here. It's shooting great and powerfully without any fine tuning necessary, so I'm going to leave it where it is. Hopefully my slug liner will show up soon and I can start shooting some varmintknocker slugs with a .0960 BC. If I can get anywhere near what Ernest said was possible with the tune kit and my slug liner, things will be looking so good! I can't even imagine a 33gr. slug with a BC of .0960 going 945-985fps. That's going to be a long distance killer for sure. I just can't wait. 

Stoti

 

[edosan]

I'm not a power junkie, but the fact that it looked like a drop in modification that would allow me to use the 51 gr pellets at higher speed seemed to be a great option.

Still disappointed?

 

[blackdiesel]

I haven't had a chance to mess with it again. But I am still disappointed in my initial results.

 

[edosan]

I haven't had a chance to mess with it again. But I am still disappointed in my initial results.

jaja of course! hope you can figure it out with all the helps you got it! been watching (since I want a PK too)

 

[ackuric]

I think with a little patience and faith, Ernest will find a way to get the .30 cal's up to par with other .30 cals on the market. FX already has the 700 mm to market which is huge for air gun performance, now they just need to work on their valves and/or probes for increased air flow, and a 800mm .357 barrel *wink*. A pcp's valve 'cycle' is in 1 ms or less, any port / air path less than equal to the bore's cross sectional area will choke/limit energy outputs. Ernest's recent affiliation with FX is fairly new, I am sure nothing but good will come of that for the future of the brand. I have criticized them myself but also aired out solutions publicly as to help with progress. I think in little to no time, some minds will be blown with whats to come.



-Matt

 

[heavy-impact]

A 700mm Impact with a DFL Ronin suppressor is a little over 40 inches long. An 800mm barrel would make the gun too long for me.

I hope the Impact V2 has the power and adjustability that everyone wants.

 

[ackuric]

A 700mm Impact with a DFL Ronin suppressor is a little over 40 inches long. An 800mm barrel would make the gun too long for me.

I hope the Impact V2 has the power and adjustability that everyone wants.

I was referring to hoping they develop something around a .357 cal in the future, a .357 really benefits from long barrels but 700mm would work just fine as well. 

Doing my math on a 10 foot barrel with a 1" bore you could generate over 10,000 FPE with the pressures we use in our pcp's...call me tempted but scared at the same time to even consider building something of that nature even just for a giggle. LOL

 

[heavy-impact]

A 700mm Impact with a DFL Ronin suppressor is a little over 40 inches long. An 800mm barrel would make the gun too long for me.

I hope the Impact V2 has the power and adjustability that everyone wants.

I was referring to hoping they develop something around a .357 cal in the future, a .357 really benefits from long barrels but 700mm would work just fine as well. 

Doing my math on a 10 foot barrel with a 1" bore you could generate over 10,000 FPE with the pressures we use in our pcp's...call me tempted but scared at the same time to even consider building something of that nature even just for a giggle. LOL

What volume of air per shot at 10,000 fpe ?

 

[Bajahunter]

Where can I purchase a Power kit for my .25 cal crown?

 

[Bob_O]

Just call Newman at FX USA

866 639 0772 Opt. 1

 

[Bajahunter]

Thank you very much Bob.

 

[Bob_O]

No problem buddy!

 

[ackuric]

A 700mm Impact with a DFL Ronin suppressor is a little over 40 inches long. An 800mm barrel would make the gun too long for me.

I hope the Impact V2 has the power and adjustability that everyone wants.

I was referring to hoping they develop something around a .357 cal in the future, a .357 really benefits from long barrels but 700mm would work just fine as well. 

Doing my math on a 10 foot barrel with a 1" bore you could generate over 10,000 FPE with the pressures we use in our pcp's...call me tempted but scared at the same time to even consider building something of that nature even just for a giggle. LOL

What volume of air per shot at 10,000 fpe ?

I don't have a formula that calculates air volume used based on FPE, I work the other way around currently. Not to say it can't be done, I just haven't gotten that far. I either calculate FPE based on air volume used @ specific pressure as well as rifle variables, or force applied to mass over distance with a few correction factors for losses.

But if I were to throw out a WAG...with the current trend in air usage that I currently see, I estimate it to be roughly 800-900~ CC's of air with at least 800-900 CC's or more of plenum (full dump), but better to have more. That is with a 6,000 gr projectile flying approximately 880~ FPS. Now that would be a true test of my formulas to verify with, lol. The 10 foot barrel volume is 1543 CC's, and generally you don't obtain any more energy after tossing an amount of air volume equal to that of half your barrel volume in cc's, in many cases 1/3rd...(depending on projectile weight)...this ones setup with a really heavy projectile to help aid that (over 1 gr per 1/2 fpe). Anyways it would be a hoot to build something like that, and considering it would be operating at fairly low pressures the biggest danger would ultimately be (IMO) stopping a theoretically 10,000 FPE projectile.



Although there could be much greater losses than I currently am predicting, I'd imagine the above isn't TOO far off of a guess. The above assumes roughly 28% of the total KE ejected from 800-900 CC's is making it to the pellet, which is typical for an air rifle operating at peak/optimal conditions, although I am uncertain how it scales! Where I make 56 fpe @ roughly 4.7 cc's, that is .08 CC per fpe, I just simply scaled that to be 10,000 * .08 = 800. Incidentally both configurations are setup to shoot similar FPS (865 vs 880). Now you can certainly increase/decrease that 28% figure by shooting well over 900 fps or well under 800 fps, and that is universal regardless of bore diameter.



-Matt