PP700 (.22cal) –– What Regulator Setting for 12FPE?

[JungleShooter]

I am a total nubee at messing with stuff that the manufacturer never meant to be messed with....

But it seems like airgunners are especially guilty of this practice....   
So, help me out. Because I've got a gun laying opened up on the operating table.... 

In put a Huma reg into a PP700S-A .22cal.

I would like to get around 12FPE with lighter pellets (JSB Express and RS).


To what bar setting should I dial the Huma to before doing a shot string with different HST settings?

Thanks!
Matthias

[USAFANG6799]

Wow "February 13, 2020," all this time gone by with no help?
It's good question because I'm getting one shortly.

[Ribbonstone]

Seems like we're ignoring you....but not from disinterrest.

By now, you probably figured it out.

Lot of us like the little guns,but the old ones aren't quite the same.. same basic mechanics,but arrived set up differently....so the advice wouldn't be as useful.

It's the energy I wanted,but with the old ones,had to work at lowering it to 12 foot pounds and I suspect you might be working a new one up in energy rather than down.

Not sure the reg setting is something I'djump on right off.....give us an idea of the size of the transfer port (in the pivoting loading block) first.

[Rob M]

prob about 1250.. i figured out the factory setting was 1450 , and that produces about 16-17

[USAFANG6799]

Good points Ribb and Rob to remember after I get mine broken in first.
I bought the dual-caliber one(.177 & .22 barrels)from Wes.
Great guy to deal with.
I encourage others to communicate with Wes before going across the pond for your airgun needs.

[Ribbonstone]

  I'd have been chasing my tail if I started right away to adjust my 700....took quite a few shots for the regulator to calm down and act like a regulator.   It settled down,then I worried about adjusting it.

[Motorhead]

80-90 bar likely all that is required.    The actuality is you will be guessing being there is no markings or test apparatus I've ever seen to actually set the reg by the numbers ..... These pistols seem to do best with lighter HST settings and adjusting reg to get at the power you want.  The specifics of the settings become rather mute.


IMO,
Scott S 

[JungleShooter]

Of course you guys are right, I eventually figured it out.

My PP700 has a Huma reg as I lost the Chinese regulator lottery badly.


🔶 As I wanted sub12FPE power, I set the reg to the lowest setting, and then adjusted the HST to get the ME where I wanted.
Worked fine.

But the gun seemed loud — even at that low 12FPE power — and despite wearing a Sumo from DonnyFl...! 😟 


🔶 So, I went back to reading Bob Sterne's instructions and a few other threads of the pro's around here....
And the solution to quieting the gun seems to be a higher rather than a lower reg pressure:  The higher reg pressure means that the air will rush into the chamber quicker, but also stop sooner to come in — i.e., the valve will be open for a shorter time (correct??).

🔶 However, WHY this setup is quieter — producing the same muzzle — I don't quite understand yet.... 🤔 
Anybody care to clear this up for me? 😊


🔶 Right now I'm shooting this .22 pistol with JSB 16gr at 14.5FPE. The Sniper Lights give me a tad more precision and flatter trajectory, but I'm waiting for the AG supply freighter from the US to deliver more....
I was going for 12FPE, but at that setting the gun was already so quiet I just kept it at 14.5FPE.


Matthias

[Ribbonstone]

Always a gunch of guesses when comapring one PCP to another of the same make/model. We expect "twins", but don't normally get that good a match.

If the PCP's gauge matches the fill device's gauge,best we can do is assume that the PCP's gauge is about right for showing where the velocity changes (likely a little under reg. setting).    So I would guess the factory aimed at something around 90-100 BAR for reg.setting.

  All the following refers to an old green grip ("bugger grip"), shorter barrel, round shroud, .22 verions sold by MrodAir. Was before the newer version, so their have been changes.

(OK...older verion might have been quieter. Shorter barrel with about the same length srhoud,more distance between barrel and shroud end....more baffling...round shroud might have had more volume than the rectangular one.)

A lot of trial and error....with a few tests just to see how fast I could go,wasgoing for lower power.

My experince was that the regulator didn't really regulate out the box. Every chronographed shot count got a bit better.  Some where about a tin of pellets(big tin) later, it was showing what I'd expect from a regulated PCP.

Was not concerned with how fast it shot during that, just so long as it shot like a regulated PCP should(low vel. varations).

It broke in and worked, but at higher energy than I wanted.

Goal was to slow mine down....wanted this .22 to be more like 10 foot pounds. Was using it as an iron sighted pistol (had to add iron sights to that version)with old man eyes,so wasn't concerned with more power than needed for 20-25 yards.

Adjusting supplied screws really isn't modding (can always adjust them back to where they started).

Those 3 really work in concert...they don't really work alone. Change one, and the others likely need changing as well.

Certainly are modifications you can do, but was hard-headed and only worked with the provided adjustments.

1. Can adjust the regulator pressure (which is pretty much a trial by error).
2. The hammer spring tension is adjustable.
3. The tansfer port is adjustable (at least on this one).Does seem the maker uses various size transfer ports as a power limiter for places with power restrictions. This .22's runs about .172".

In my case, considering the time it took to get the regulator broken in,elected NOT to change the reg.

Changing the hammer spring tension had it's limits. Less than a certain amount of tension resulted in wide velocity varations(expect that lowering reg. pressure would have fixed that). Set it for less tension, but higher than the uneven velocity varation setting.

Almost to goal....still a little fast. 

Restricted the transfer port bit by bit.  Found another place where restricting any more resulted in wider velocity varations .
So adjusted down, but up from the point where "stupid"started to happen.
Ended up at 9.5 foot pounds as as low as this set of factory parts could be adjusted and maintain a nice even velocity. 


---------
Cranked it a bit back up in power when it got made into a scoped carbine..also added an LDC.

Jungleshooter: not real sure.Noise is a matter of pressure and volume of ejected air....more about how much air and pressure at the muzzle than what what pressure we started with.

Do think a short quick "blip" of high pressure can be quieted better than a long "burp" of lower pressure air,simply becasue of the volume part of shrouds/LDC's.

[subscriber]

When you shoot an unregulated PCP to get a full shot string, it gets louder as the reservoir pressure drops towards the end.  This is because the valve is not being closed as quickly with lower air pressure pushing it shut.  The result is that the muzzle pressure ends up being higher, making the gun louder.

Increasing the regulator pressure, and using a very short valve duration enables the same average air pressure down the bore (that, and the barrel length set the FPE).  However, with a short burst of high pressure air, the pressure profile down the barrel is very "spikey".  Most of the pellet acceleration occurs in the first quarter of the barrel length.  Thus, with the valve closing with the pellet 1/4 way down, the small fixed volume of high pressure air behind it then expands into the remaining 3/4 barrel length.  Thus the pressure at the muzzle is only 1/8 what it was when the valve closed.

Bob has some good posts showing pressure graphs for various tunes.  He can also explain it better than me.

In firearms terms; a high reg setting used for low power is like using a small amount of fast burning propellant.  A low reg setting is like using more of a slower burning propellant to achieve the same power.  The slow propellant is not very efficient in accelerating the bullet, but is still burning when the bullet exist the muzzle.  The latter makes it louder.  Louder is thus a sign of poor efficiency.

[JohnnyPDX]

..... These pistols seem to do best with lighter HST settings and adjusting reg to get at the power you want

I've found a good shot count and accuracy with the HST turned in 2.5 to 3 turns (low tension like MotorHead said). The starting point is the obvious one... when the bolt is flush with the top of the nut. At the "zero" starting point of adjustment there no tension on the hammer spring.

[anti-squirrel]

My PP700 is one of the older ones here on the GTA (only person that remarked having one before me was Robert AKA ribbonstone).  Like him, I shot a bunch before touching the regulator, but I definitely won the regulator lottery (as well as the barrel lottery!).  It came from Krale shooting 14 FPE in .177- a real firecracker.  I dropped it down to as low as 8 FPE and back up to to as high as 16 FPE, but have settled on 95 BAR.  It wastes a tiny bit more air than when set at 90 but the bark is not as loud.  With HST and TP as currently set, it is 12 FPE on the button with Sniper Magnums- one of the heavier .177 pellets.  These are not the most accurate pellet (likely tied for 3rd-best with 5 other pellets) but they are easy for my hands to load, so I shoot them a lot.  I have roughly 19,000 pellets through mine.

[Ribbonstone]

It's going to depend on what he gets in the box.  Some were made for non-US markets and show up limited in power (most likely by way of a really small transfer port.breech block).
Some are advertized as 16J....which is reasonly close to 12 foot pounds if the advertized energy is accurate,so he may not much adjusting to do.

Not sure I'd do any of that without a chronograph...without, it's pretty much like a tone deaf guy trying to tune a piano.


On a budget?
HAve tried a $28-$35 clamp on China-cheapie....odd as it seems, was within 1.5% of a full sized (more expensive) unit. More important than the 1.5% is that it reads consistantly.