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

[gendoc]

i will be checking in with Lee, thank you !!!!

[JungleShooter]

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

Roachcreek,

you bring up something that I have been wondering about: 
🔸Where to place the chrono —
🔸and what muzzle velocity number to use in my balllistic calculator....

You write you "corrected to the muzzle".
🔸Is that necessary?
🔸How do you do that?

Thanks for enlightening my ballistic twilight.  🤣

[MB]

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 !!

Pyramid Air - replacement barrel for the CZ 200

[Lani52]

Matthias,

I placed the chronograph directly in front of my target, I shot from 10 yards.  Using the AA AIRGUN CLASSIFIED bullet calculator I increased the velocity until it matched my 10 yard velocity I achieved on my chronograph,  then read my 1 yard velocity on the ballistic calculator. 

I hope this makes sense.

Roachcreek

[JungleShooter]

Roachcreek, that makes sense, thanks.


My Skyhawk seems to spew something out besides just 15.89 grain pieces of lead.... 
Wonder if this is normal (it's my first PCP, still got to learn lots).
Anyhow, it seems like there is something like water vapor (🤔) coming out, for about a foot or a foot and a half beyond the muzzle I can see it....

Any clues...? 🤔

[gendoc]

Pyramid Air - replacement barrel for the CZ 200

i have been instructed that these barrels are too short for the skyhawk.

[Lani52]

Okay I am getting very close to 47 FPE and do get a few at that power at the height of my regulat4d string.

So let’s talk about shot count:
Before the  plenum extension I was getting around 70 28 FPE shots with 14.3 Crosman HP’s. 
After the plenum extension, and with a hammer spring adjuster flush with the receiver, I was at 40 shots@42 FPE with 22 cal 25.3 and 33.9 grains.
Now at three turns in I am at 46.67 to 47 FPE I get 36 shots before dropping off the regulator.

Bear in mind I am not filling to 3625 psi, I am filling to 3500 to 35504 PSI.  This is due to the fact that the P-15 design blows out the fill port oring if I creep over 3625 PSI and I get tired of replacing that oring for the sake of a couple more shots I don’t need for the trouble it is to get them.


Roachcreek

[gendoc]

who makes the regulators thats in the skyhawks ?
mine is a gen-I.
reason i ask is, the huma power plenum is what i'm interested in.

[Lani52]

Matthias,
Sorry I missed your question about the water va-er coming out of you Skyhawk.  It sounds like your inadvertently putting water in your rifle.  How do you have your high pressure air?

John,

I think Snowpeak makes their own regulators.  You can buy them on eBay, but I never read the adds.

Roachcreek

[JungleShooter]

Handpumping w/ FX 4-stage.
65ºF / 18ºC
85% humidity
30" Hg / 1015mB

[Lani52]

Matthias,

Pressurized air can lead to condensation also, having said that 85% humidity will give you moisture in your airgun.  Some hand pumps, such as the Hill mk4 and I think the mk3 have moisture filters. 

I live in the High Desert, I have around 35 to 45% humidity in my air conditioned house and I run a air filter on my Shoebox inside the house.  When  I was pesting on the vineyards in western Oregon the humidity was very high and My scba ranks would spit air when I filled some think this can cause corrosion in PCP tanks, I always inspected my airgun  tanks for corrosion and have never noticed problems.  The writer of the Pyramydair blog, Tom Gaylord says it just shoots out the moisture when you shoot the your airgun. 

So the jury is undecided, I however run moisture filters and check my air gun tubes when I depressurize and work on my airguns.

Hope this helps.

Roachcreek

[TF89]

Regarding seeing a small vapor cloud when shot.  I use dive shop scuba air and I will see the vapor trail on occasion.  In my case and since very dry air is being used I'm thinking it is more related to moisture in the air and if the temp of the gun when shooting is warmer than outside temp.

[MB]

Pyramid Air - replacement barrel for the CZ 200

i have been instructed that these barrels are too short for the skyhawk.

Who told you that ? These barrels are over an inch longer than OEM - Lee just did mine -See below:

[MB]

I also reduced it by a few mm to have the same thread as original p15/ skyhawk

[gendoc]

Pyramid Air - replacement barrel for the CZ 200

i have been instructed that these barrels are too short for the skyhawk.

Who told you that ? These barrels are over an inch longer than OEM - Lee just did mine -See below:

maybe i was mis-informed, it happens from time to time on the web....
was it Lee 545 that did your barrel machining ?

[MB]

Pyramid Air - replacement barrel for the CZ 200

i have been instructed that these barrels are too short for the skyhawk.

Who told you that ? These barrels are over an inch longer than OEM - Lee just did mine -See below:

maybe i was mis-informed, it happens from time to time on the web....
was it Lee 545 that did your barrel machining ?

Yes it was he had no problem doing it...comes threaded 1/2 unf but I wanted it changed as i wanted the stock shroud...

[gendoc]

Pyramid Air - replacement barrel for the CZ 200

i have been instructed that these barrels are too short for the skyhawk.

Who told you that ? These barrels are over an inch longer than OEM - Lee just did mine -See below:

maybe i was mis-informed, it happens from time to time on the web....
was it Lee 545 that did your barrel machining ?

Yes it was he had no problem doing it...comes threaded 1/2 unf but I wanted it changed as i wanted the stock shroud...

i understand about the stock threading, i have a Rocker1 custom LDC coming
in that thread.
do you have the Huma power plenum installed in yours ?
and  BTW....thatsa very nice look'n skyhawk you got there !!!
i bet she is a sweet shooter...

[MB]

Pyramid Air - replacement barrel for the CZ 200

i have been instructed that these barrels are too short for the skyhawk.

Who told you that ? These barrels are over an inch longer than OEM - Lee just did mine -See below:

maybe i was mis-informed, it happens from time to time on the web....
was it Lee 545 that did your barrel machining ?

Yes it was he had no problem doing it...comes threaded 1/2 unf but I wanted it changed as i wanted the stock shroud...

i understand about the stock threading, i have a Rocker1 custom LDC coming
in that thread.
do you have the Huma power plenum installed in yours ?
and  BTW....thatsa very nice look'n skyhawk you got there !!!
i bet she is a sweet shooter...

Yes she is custom built from scratch P15 in 177 Caliber, custom stock and many internal mods, modified spring, hammer, valve stem , larger Transfer Port and many others, just finished assembling her last week, she is a 177 caliber and yes it has HUUBS Power Plenum and Reg from Huma. I spent some time encouraging Huub to develop one, he sent me and one other lucky guy plenums to test... 12cc plenum - lower reg pressure shooting JSB 10.34 at 915 fps, Reduced hammer spring tension and I am getting somewhere around 70 -80 shots per fill...Lost count last time around Lee is your guy to do the barrel, shot 50 pellets at 28 yards through a thumbnail size hole and she has not been leaded in properly...Extremely accurate...

[gendoc]

from the huma power plenum page, it asks for this information...

IMPORTANT NOTE BEFORE ORDERING:

Artemis/Spa/Diana uses different ways of machining inside the pressure tube. To make sure we will sent you the correct model we need to know the position of the "step" inside the pressure tube as shown on the picture below. Size X can be smaller as 82 mm or larger as 82 mm.
Please select the correct model of your pressure tube in the drop down menu in the order field.



anyone here ordered the power plenum for the skyhawk and know what this
inside "step" Dimension is ??

i thought that the only difference was cosmetics and branding ??
but i am wrong occasionally.....

[Lani52]

I tried shooting 14.3 Crosman Ptemier hp’s this morning with the preload backed out to flush.

I wanted to see what amount of adjustment I could get with the plenum installed and if the velocity was stable at low hammer spring preload.  I had sketchy chronograph readings before the plenum was installed, but if memory serves me correctly, it was in the 900-910 range after tuned by JSAR.

I fired a magazine of the 14.3 Crosman at 10 yards from the Caldwell chronograph and then calculated the velocity to the muzzle using a bc 0f .025.
The result was I had a range of muzzle velocity from 910 to  915 psi, most shots were 910 to 915 FPS.

So it appears I can have a FPE range from 23 FPE to 47 FPE simply by adjusting the stock hammer spring.  I find this amazing for a regulated rifle.

Riachcreek