How to Tune the Skyhawk .22 from 32FPE to 38FPE?

[JungleShooter]

How to Tune the Skyhawk .22 from 32FPE to 38FPE?

I have a Skyhawk .22 with a LW choked barrel, and Huma reg (setting unknown).
It shoots the JSB Domed at 925fps (30FPE) and the Baracudas at 830fps (32FPE, 2FPE more than the JSB).

I’d like it to shoot the JSBs with 970fps (33FPE) and the Baracudas with 860fps (35FPE).
How do I go about this? I’m no gunsmith, but I think between the videos on the tube I’ll figure out how to take things apart and put’em back together without having left-over pieces at the end....



Another question....:  Is it even advisable to do so?!?

To understand my situation:   
I’ve been trying to evade them, really! – but in the end they still got to me. And now I belong to them, they own me.
Them, that is – the long-range pixies.
I have to blame them for this unrelenting urge to shoot long-range (100y and hopefully beyond), and as they make their high-speed low-altitude passes up and down the valleys of my desert hills, it is their fault that the winds are always howling, soooooo....
I need high-BC projectiles. Which either means (a) heavy domed pellets – (b) or slugs.

By getting the muzzle energy a little higher I’m thinking I would be giving those slugs better stability downrange (the barrel is a LW with 17.7 twist rate, not particularly fast, if I interpret the ...).

(A side benefit of higher muzzle energy:  I’ve been looking at all those nice hollow-points with a relatively high BC – H&N Hunter and Hunter Extreme, JSB Metalmag, even the Hades (with a fairly low 0.024BC).  These would really open up nicely if they hit my critters at higher speeds....)


Thanks for your help. I got lots to learn here. 

Matthias

[gendoc]

i'm watching this because i have an offer out to a person wanting to sell
there skyhawk.
according to the owner, its a 33fpe gun with 18.13gr jsb.
i would like to increase that as much as i can and still have stability.
thanks

[Pelletjunkie]

If you want to shoot far and kill things, accuracy comes before speed. You are already close to the limits at 925fps. My Taipan and Priest ll will both go into the mid 900’s. They do acceptable out to 50yrds. To get my best 100yrd groups, I have them set around 900fps. The 50yrd groups then improved also. Your Skyhawk is light and made in China, staying around 900 will keep the shot cycle smooth and the gun reliable.

[Lani52]

I am watching also. I want more than the 28 FPE it came with new and to shoot heavier pellets, 25 to 32 grain.

I just got my 22 caliber Skyhawk back from Lee545 having  his 25 cal plenum extension put in , regulator set to 140 bar from 130 (Huma).  I have the  longer 20 inch LW poly choked barrel, so not suited for slugs,  and all the required porting.

I have not chronied it yet.

Not interested in slug shooting with it as I already have a 615 yard video on utube on line of me breaking 12 oz cola cans at 500-550 and 615 yards, not to mention I can’t see that far anymore.

More interested in which spring and what preload.

Roachcreek

[anti-squirrel]

Diabolo shape pellets at nearly 1000 FPS?

Nope.  I'd focus on heavier pellets, not lighter existing pellets edging on trans-sonic.

[Hobbyman2007]

Gentlemen ,

In my experience playing with a variety of guns from the QB78 and through to FX and just about everything in between . Making power is usually pretty straight forward . Big ports , big spring and heavy hammer usually get the job done . Getting the balance right so that the gun is still shootable and reliable . Over stressing components is not something to be taken lightly , overfilling being the worst kind .

Before tearing into these guns , and drilling everything out ,and installing a massive hammer spring . I would go through them carefully and making sure that all the ports are lined up and the air flow is as unrestricted as possible . Having port diameter changes is a real power killer in PcP’s . I’d go to no more than .170” , lean on the hammer spring if needed by shimming before replacing .

[gendoc]

  I have the  longer 20 inch LW poly choked barrel

Roachcreek

where did you get the LW barrel from and was it a direct fit, or
did you have it machined ?

[MB]

Based on you already having a LW Barrel, I would increase hammer spring tension, reduce valve stem diameter to 2 mm and add a power plenum, I have one from Lee AP on this forum and have been working with Huub at Huma Air who sent me a 12 and 16cc power plenum to test, unfortunately both my p15's are being re-barreled to LW and CZ barrels at present, so I have been delayed in testing, HUUB has in the meantime however already brought the plenums to market....

https://www.huma-air.com/Artemis-P15-Power-Tune-Regulator-XL-Plenum-Set

There some other areas you could gain as well such as porting...Others have already done so successfully...

[gendoc]

My offer was accepted for the used skyhawk.
It should be here this weekend.

A CZ or LW barrel is needed 

[Lani52]

Gendoc,

I had JSAR machine the barrel, during the process they asked me what length I wanted as I had asked them to do.

I requested a 20 inch barrel.  I got it back just as they were starting the Raptor project.

The LW barrels are undersized and require brass bushings to fit the rail supports I have no idea what the Cz barrel diameters are

My quest for power involves using jsb’s In the 25 to 32 grain range not light weight pellets. When I bought it PA did the 10 for 10 test for me but used 11 grain pellets, go figure.  I shot some 14.3 crosman hp’s chronied at 11 yards at 905, so at the muzzle they were going much faster, very accurate but not at all what I wanted so I had the plenum put in and did a order for the heavier jsb’s.  I  personally have no desire for the lighter pellets at Uber velocity.

I have just put it back together after Lee returned it with the plenum extension, I have mounted a Bushnell AR4.5x18 on it but not tested it yet.

 I

[gendoc]

Gendoc,

I had JSAR machine the barrel, during the process they asked me what length I wanted as I had asked them to do.

I requested a 20 inch barrel.  I got it back just as they were starting the Raptor project.

The LW barrels are undersized and require brass bushings to fit the rail supports I have no idea what the Cz barrel diameters are

My quest for power involves using jsb’s In the 25 to 32 grain range not light weight pellets. When I bought it PA did the 10 for 10 test for me but used 11 grain pellets, go figure.  I shot some 14.3 crosman hp’s chronied at 11 yards at 905, so at the muzzle they were going much faster, very accurate but not at all what I wanted so I had the plenum put in and did a order for the heavier jsb’s.  I  personally have no desire for the lighter pellets at Uber velocity.

I have just put it back together after Lee returned it with the plenum extension, I have mounted a Bushnell AR4.5x18 on it but not tested it yet.

 I

thats good to know, and i hope your performance is to your liking.
now i must find out about the cz barrels and where to purchase a blank.
my taipan has a cz barrel and its very accurate and reliable like we all know the taipans are.....
thank you !!

[Lani52]

I shot the Skyhawk today, went from 2 turns in on the spring, then worked up to 4.5 turns then back to 4 turns in on the hammer spring.

Still very quiet but then I have a longer, larger diameter shroud to mate with  the 20 inch barrel.

Right now in duct seal, 22cal 25.39 Jsb’s are very quiet and accurate, maybe shot 15 8 shot one hole groups.

My cheap chrony has passed on, the battery terminal will not take the 9 volt ends and touching the terminals does not breath life into it.  Being as indoor chroning and light is a problem, I am considering the wireless fx chronograph as the fact it works in the dark is a heads up for indoor chronygraphing.

So to test my Power without a chrony, I measured penetration into duct seal. My 500 fps prod buries 14 .3 grain pellets flush to the skirts, my Seneca 25 carbine puts 43 ej’s Into duct seal to where they are 1.25 inches to the skirt, the Skyhawk duplicates this penetration.
My regulator is set at 140 bar, without the extended plenum, at 130 bar, I was getting around 905 at 33 feet with 14.3 hp’s and 70 shots, 820 FPS with 18 grains. The Skyhawk is now getting around 40 shots.

So what does the penetration comparison mean?

It may mean that it will shoot 25.39 grains flat for 400 yards and then start rising!  Most likely though it means my chrony is broke, sort of like having a broke speedometer and rear ending cars to test your speed.

Regards

Roachcreek

[Lani52]

I shot 4 darko mags with the 14.3 Benji’s, they shoot little one hole groups like before, still very quiet, but those 40 shots took the tube pressure to 120 bar not 140 bar, so 3500 psi to140 bar is around 32 shots.

So it would seem I must be taking benefits from the plenum extension, noise being low leads me to think the shroud is working fine and not pushing that double dose of air out the muzzle.

I feel confident that I am making a lot more polite power, meaning subtle sound and great accuracy, but I am going to need to spend a couple hundred bucks for a pcp speedo to know for sure.

Regards,

Roachcreek

[Lani52]

I ordered a Caldwell chronograph and light kit to replace the non working, never working inside chrony.

A pcp owner should never be without a speedometer.

I am really liking the way my Skyhawk turned out.

Roachcreek

[JungleShooter]

Thank you all for chiming in.  😊
I'm still eager to hear more comments on how to tune up the power.*
And on the wisdom (or folly) of doing so in the first place.

*(not to 40 or 50FPE, but say 36 or 38 max.)


Roachcreek,
it sounds like you have a real nice gun now. I have accompanied your Skyhawk journey from terrible shooter to terrific shooter — and I'm happy for you that it worked out!


Matthias 

[Lani52]

Okay I have some Skyhawk numbers.
Lee545 plenum extension
20 inch LW poly chocked barrel
Huma set at 140 bar
Brand new Caldwell chronograph 3 feet from muzzle and 12 yards from muzzle
JSB 25.39

Two turns in from flush=859 FPS at 3 feet, 828 FPS at 12 yards.

3 turns in = 874 FPS /43 FPE

Next I will try the 32 grain JSB.

First I need to stop giggling.

Roachcreek

[gendoc]

Okay I have some Skyhawk numbers.
Lee545 plenum extension
20 inch LW poly chocked barrel
Huma set at 140 bar
Brand new Caldwell chronograph 3 feet from muzzle and 12 yards from muzzle
JSB 25.39

Two turns in from flush=859 FPS at 3 feet, 828 FPS at 12 yards.

3 turns in = 874 FPS /43 FPE

Next I will try the 32 grain JSB.

First I need to stop giggling.

Roachcreek

wow!!!
tell us more about Lee's extension 

[Lani52]

Well 33.9 5 were doing 755 FPS which again is 43 FPE.

Yes the Lee 545 25 caliber plenum. If I remember correctly, Lee 545 made it for the 25 caliber P-15, but it obviously works on the 22.  It screws onto the valve body and the end of the Huma, fitting in between the regulator and the valve, doubling the plenum volume.

I had trouble getting it sealed as I ran out of divers grease and I just don’t have enough vision left to sort it out.  Lee was making me a replacement shroud to correctt the bum workmanship of SnowPeaks p15 shroud, so I just asked him to install it which he easily did.

He charges 77 bucks for the extension.

[JungleShooter]

I appreciate the info, thanks! 

Makes me wonder if I need this plenum extension, too....
Need, yupp, in airgunning those things aren't wants, but needs...!!   

[Lani52]

Yes John and Matthias you need that plenum extension!

I did some more work with my chronograph, but this time I set things up better, for the Chronograph angle to meet the Skyhawks angle, and I shot at 10 yards. 

My highest velocity with the 25.39 22 JSB  was 857 FPS, which corrected to the muzzle is 904 FPS/46 FPE.

Basically I picked up 18 FPE with the plenum extension and more preload, but bear in mind I have a 20 inch barrel.

I also have to say how much I am enjoying the Bushnell AR Optics 4.5x18 as I can see the reticle so clearly.

Roachcreek