PP700 adventure started(Artemis PP700s-a)

[Kid Shelleen]

I’ve tried just about everything else so I turned in (CW) the regulator screw about 30° and closed off the transfer port 2 ½ turns (CW).  I filled to 145 bar (my tank was running low).  Here’s the string from my son's gun.

145 bar fill:
752. 618. 632. 636. 638. 638. 647. 638. 642. 646.
648. 650. 648. 652. 655. 658. 667. 660. (90 bar). 665. 663.
665. 662.  664. 664. 662. (70 bar). 673. 668. 670. 666. 658.
651. (60 bar). 635. 623. 607. (55 bar).


Starting with shot number three at 632 and ending with shot 31 at 635, there was 30 shots with the low of 632 and hi of 673.  Extreme Spread was 41 and Standard Deviation was 11.95 so it’s shooting at about 6%.  Not good but better than it was doing with my other low end settings.  I also did some pre testing before shooting this string and found that if I waited a full minute between shots, I was getting about a 20 to 30 fps increase with this setting instead of the 80 to 100 fps increase using my previous setting so it looks like the regulator creep has been lessoned (if that is the correct term).  I think I have about ¼ to ½ turn (CW) left on the transfer port screw.  Next time, I’ll try turning in (CW) the regulator screw another 5° to see if I can get rid of any more of the regulator creep and may try closing the TP another ½ turn if it will go that far and see if that helps.  So far it’s not close to my PP700SA that got an ES of 15 and SD of 3.45 (Note:  I made a mistake in one of my previous posts where I said for my gun the ES was 35 and the SD was 8.  Those numbers were from a previous tune.)

One question I have is about regulator “setpoints”.   If I’m understanding correctly, the setpoint is the pressure setting (say 80 bar) where the regulator is actively working (regulator is acting like a regulator) but once the pressure in the vessel drops below that “setpoint”, the regulator is no longer active and the air pressure in the vessel takes over.  If this is the case, (on a PP700) does screwing in (CW) the regulator adjustment screw, raise the setpoint (say from 80 bar to 100 bar) or does it lower the setpoint (say from 80 bar to 60 bar)?  Also, what do you think an average setpoint would be for this gun with the above listed settings.  Is my guess of around 60 bar even close?

Thanks for all your help.  Shelleen

[Wayne52]

Try this image I borrowed from the facebook group.  This is of a W model, but the parts are the same.

Thanks for the fantastic inside pic of the P700 Donny !!!

[bandg]

Turning the regulator screw in (CW) does raise velocity (if balanced with hammer spring spring pressure) so it must be increasing "setpoint.  I'm absolutely not a regulator expert and haven't disassembled that far into the pistol yet but it seems you view the regulator function the same way I do.  I do view the transfer port utility differently.  It seems that increasing the regulator and hammer spring to increase available air flow and then turning the transfer port in to reduce it would be counterproductive to a degree-"wasting air" so to speak.  I decided initially (after reading all threads on the pistol) to port and set the transfer port open for maximum flow and then tune with the regulator and hammer spring.  Could be entirely off base as to how the system functions but it has worked very well for my pistol (highest effective velocity desired) with it providing 930+ fps with 7.33 gr. .177 and excellent accuracy.

[bandg]

Bizill, I believe from looking at the diagram Donny provided that you had the base of the air tube still in place.  I have had the air tube off but haven't disassembled the base and regulator section.  I believe that after the air tube screws off the black base (left of the silver threaded part indicated by the upper arrow) that you then have to unscrew the black base from that silver threaded part before you can see the screws.  That is what I saw when I had the air tube removed-that black base was still attached to the silver regulator body on the right.  It appears that the silver part (upper arrow) screws into both the air tube base on one side and the "regulator body" (that has the screws) on the other side.

My TRRobb fill probe was the same.  It wouldn't fit into my foster female fitting.  I put it in my drill press and spun it against a file to remove just enough material from the outer surface of the end ring to allow it to fit then repolished that area.  Should do it slowly so you don't remove too much and possibly make it loose.  Works fine in mine now with no leaking.

[Bizill]

You're right.  That's exactly the case it seems.

Regarding T Robb, I've emailed several times to no avail.  Started a Paypal dispute so we'll see how that goes.  I could have made the fill probe at my work for free but wanted to support a fellow hobby enthusiast but it didn't work out too well this time. 

[Wayne52]

I've never had any problems with the TRRob fill probe, it's been working great

[bandg]

If I had to guess, I'd think that the issue may just as easily lie with the female fitting and not the fill probe.  Seems machining that fill probe to the correct size would be pretty easy.  But something prevented them from fitting for at least two people (2 separate probes in my case).  Glad they go right in for some people but not the case with all.

I originally ordered 2 of these from TRRobb and had left one sealed in plastic.  I just measured them both.  The unmodified one measures .314" in most areas but measures .316 in one spot and it also will not fit into the female end on either my hand pump or the Tuxing compressor.  The one that I modified to work measures .311 and fits and fills from both pump and compressor with no leaking.  Not good that they won't fit as sent but again hard to say whether the probe or the female foster is out of spec.  They are easy enough turn down to fit so not worth the trouble to return for me.

[Bizill]

I'll say it's the probe.  I have cheap and legitimate Foster branded females and his probe doesn"t fit any of them, period.  I'm sure he's busy and will make it right.  Maybe not.  Don't know if he's even a member on U.S. forums and is aware but I've hit him up more than a few times.

[bandg]

Sure sounds like the probe is mis-machined then.  Post any response you get from him please-I may try to exchange the second one if he acknowledges an error.

[Rallyshark]

Turning the regulator screw in (CW) does raise velocity (if balanced with hammer spring spring pressure) so it must be increasing "setpoint.  I'm absolutely not a regulator expert and haven't disassembled that far into the pistol yet but it seems you view the regulator function the same way I do.  I do view the transfer port utility differently.  It seems that increasing the regulator and hammer spring to increase available air flow and then turning the transfer port in to reduce it would be counterproductive to a degree-"wasting air" so to speak.  I decided initially (after reading all threads on the pistol) to port and set the transfer port open for maximum flow and then tune with the regulator and hammer spring.  Could be entirely off base as to how the system functions but it has worked very well for my pistol (highest effective velocity desired) with it providing 930+ fps with 7.33 gr. .177 and excellent accuracy.

You are correct that it may be counter productive on the air use front.  However, it has been shown over and over that these guns don't like the low power tunes well, or not the "full power" guns at least.  It may come down to nothing more than a different belleville arrangement on the 5-6fpe guns across the pond, but I don't know that for sure.  In Mike's case, that particular method of choking it down with the transfer, is the best way I can think of to negate the pressure variations he's seeing.  That is short of playing with the belleville stack.  If he were to do that, I say try ))(())(()), and polish the washers lightly on a wet stone.  I'm certainly no regulator expert though  

Try this image I borrowed from the facebook group.  This is of a W model, but the parts are the same.

Thanks for the fantastic inside pic of the P700 Donny !!!

That image is courtesy of Klaus H., who is the admin of the facebook group.  He does a great job of documenting his work and taking very informative photos!  I wish he were on GTA, because I feel sure he'd have a solution for these lower power tunes.

One more thing, I ordered that stainless fill probe from T Robb and it arrived but was made too big.  It won't fit in any of my female foster fittings.  The O.D. on the male foster is too big.  I'm not gonna try to sand it and don't want to have it turned down at work.  Anyone else have a problem with theirs?  I've emailed T Robb a few times over the past week with no response.

I have the LDC adapter from him, which I got before Rocker1 started making them, and I had to do some "fine tuning" on it to make it fit properly.  Granted, it was easy to do.  Not to poo on Trobb, but he is often referred to as "the robber" on the facebook page,lol!  Take that for what it is worth I guess.  His machining looks good, but his tolerances are often a bit off from what I've seen.

[Wayne52]

The diameter of mine at the foster fitting is .313.

[Kid Shelleen]

Bandg, thanks for the information on the setpoint.  I think you’re correct about the best way to tune is using the regulator and hammer spring (that’s what I too have read in my research) but on this gun, my son’s, I want to tune it for low/medium power and this regulator seems to have more reg. creep issues at low power.  The dozen plus setting I’ve tried using just the reg. adjustment, hammer spring tension and various starting fills, have been pretty bad and I was getting speed variations up to 100 fps by waiting 60 seconds between shot and 20 seconds between shots.  On my own PP700SA, the regulator is a little more stable but to get the tune I wanted, I still had to restrict the transfer port.  I did the same thing with a couple of .177 Disco’s.  I wanted to “detune” them to shoot in the 800 fps range and in order to get good flat shot strings, I had to put a smaller transfer port in them (challenger TP drilled out to around .065” if I remember correctly), then fiddled with the hammer spring adjuster and the fill pressure and was able to get a pretty good tune.

I think a little later on I’d like to try and take my son's PP700 apart and take a look at the O-rings, mating surfaces of the valve (thanks Jason) and such for possible leaks and try cleaning up and rearranging the Belleville washers like like Donny suggested but that will have to wait for a while.   I gave the gun back to my son because I was feeling guilty keeping it so long trying to tune it.  He’s happy with the current tune and is going to shoot it as-is for a while.  I’m glad I had a chance to work on it though because I learned a lot about tuning this gun from all the great information I got from the people here.

I’m still curious though about the set point on these guns (in .177) when they are shooting in the 650 – 700 range.  Anyone have any information or guesses.  I think for this gun it may be in the 70-60 bar range but I’m just guessing.

[Rallyshark]

I think you may be close on your guess for the factory reg setting in .177 at least.  Mine was rather low when I got it.  I hand pump, and I couldn't get that valve to seal for nothing after I did my valve work.  I could get it up to about 80 bar pumping like a maniac with it still leaking.  My gut was telling me the reg set point wouldn't let the pressure get high enough to get that valve to properly re-seal.  I re-arranged the belleville stack, and tightened down the reg adjustment, and it sealed right up when I got to 80 bar, and it wasn't leaking at that point either.  After all of my messing around, I think my reg is running around 120 bar now, which is exactly what I wanted to maintain a good power tune.  It will maintain 1000+fps on reg with the 7.25 grain pellets now   I have it tuned to 900fps with those same pellets that I use for critters, and I get 30+ shots at that power level.  Once you find the magic combo to work for what you want, these things are awesome!

[Bizill]

Factory probe .312.  That .002 makes the difference between go and no-go.  I know I can alter it but choose this time not to.  It's a simple enough item to machine to tolerance.  It's not just the machining of the O.D., the whole thing looks to have been finished by belt sander.  I've reached out via Paypal.  He responded by asking me to outline the problem and give my order number.  All of which I've done in the first 3 emails.  Now all I hear are crickets.

[Wayne52]

I tweeked mine with the hammer spring and the regulator but I'll bet you could very successfully use the valve poppet spring adjustment along with the other two as well.

[nervoustrigger]

The valve spring generally is not useful for tuning a regulated gun.  It can be for a conventional unregulated PCP because it plays a role in the self-regulating behavior. 

[sawtoothscream]

Haven't had a chance to play with my tune, but man what a fun gun. Took it for a nice hike yesterday just shooting little pieces of broken clay pigeons that seem to be all over the place.     Had many chances at reds but they were no bigger then chipmunks so I passed on them.   

[Wayne52]

Jason I did notice if my hammer spring was as tight as it would go that it wasn't enough for what the regulator can do, I was thinking I might be able to eke out more energy with loser tension on the poppet spring

[bandg]

I did try that Wayne and I believe that Jason is probably correct.  There might be some energy gain with a lighter poppet spring but balancing it against hammer spring pressure seems to be difficult.  I had made a new spring that was lighter than stock to the point that I had to cock the hammer to fill the gun.  My thought was to maybe pick up some energy but also to keep hammer spring preload lower to keep trigger pull weight as light as possible.  Once filled it would seal and fire normally and it did seem to gain some velocity but it also dumped the tank well before all usable air was exhausted.  This method might be fine for maximum velocity tunes if a person were willing to disassemble and reassemble multiple times to vary the poppet preload and shoot multiple strings over various fill pressures and then analyze for the "sweet spot" but almost certainly not for anyone concerned with long shot strings.  I am currently back with the stock spring and will probably play with preload on it some if it is apart for some other reason but basically I believe that the energy of the hammer impact is sufficient to provide good consistent valve function.  Optimized?  Probably not but it seems pretty close.  And getting it optimized would take a lot of work for an unknown gain.

A good but time consuming (and possible disassembly wear issues) experiment would be to set the stock poppet spring to maximum preload (just before coil bind on full stem movement) and then shoot strings while varying hammer spring preload across the fill pressure range.  Then disassemble and turn out valve adjuster a turn and repeat.  It would require multiple disassemblies, lots of shots and fills, and really good records but might allow a perfect setpoint to be located for both valve spring and hammer spring.  Might be worth it to some but wear and time says no to me. 

[Rallyshark]

I have my valve spring about as tight as it can go, and it has been there since I first modded my valve.  I'm pretty sure my regulator is near the limit on the high end(120-ish bar).  I feel like the hammer/valve spring is well matched to my particular setup.  While I have it tuned to around 15fpe(depending on the pellet used), it still has enough hammer spring adjustment in reserve to take it up to 20fpe(.177)