PP700 adventure started(Artemis PP700s-a)

[aluminumfetish]

well, my pp700sa started to leak. I knew it just a matter of time. She leaks down slow over about a week. I have the o-ring kit that came with it. (seems like they are the same inferior rings that are already leaking). I am probably going to pull her apart to at least put the replacements in. I know there was chatter about better replacement rings. Any advice for my first trip into my pistol ? I WILL degas it of course... it de-gasses itself

[nervoustrigger]

Mitchell, Buna-N is a good material for the replacements, either 50 or 70 durometer. 

The factory O-rings swell up like mad, a symptom fairly common with CO2 but this is the first time I've experienced it with high pressure air.  I wonder what they are made of.  Neoprene, perhaps?  They also appear to be prone to compression set.

Anyway, no real need to splurge on polyurethane except perhaps for the one that seals the rotating breech block since it's subject to abrasion.

So far mine has leaked in two places, and one of those was a result of me disassembling and reassembling.  I wrote of it a few days ago in this thread but it's where the two halves of the regulator thread together.  Apparently it's supposed to seal against the white plastic washer inside but it's hard to develop enough torque when reassembling.  Fortunately it's easy to remedy by adding an O-ring as Bob described in this post https://www.gatewaytoairguns.org/GTA/index.php?topic=121844.msg1290844#msg1290844
I would not be surprised if many of them have a slow leak in that location.

The other leak was at the fill port.  I used a -009 Buna-N to replace the factory O-ring.  Really easy to replace that one. 

[aluminumfetish]

thx Jason. I will post my progress.

[Ozarkairgunner]

Hey guys, I know a few of y'all are getting your pistols shooting up in the mid 800s to low 900s by restocking the bellievew washers, but to my knowledge most of y'all that are getting that are shooting .177 and using a reg stack like this (( )) (( )) ((. Let me know if that's right or not please. But using that same stack design with the .22 is will only achieve a high of 675fps-ish average. I've adjusted my valve spring pressure and hammer pressure quite a bit to get those results. Does anyone have any ideas on a better stack design to achieve higher set pressure.

[nervoustrigger]

CJ, nesting (paralleling) them in groups of 3 will give you a higher spring rate and therefore a higher setpoint.  You could use 9 of the 10 washers in this arrangement ((( ))) (((

That will make the overall stack shorter, and that is not so much a problem in and of itself but it could possibly affect how the little cup-shaped adjustment screw interfaces with the stack.  It's probably easy to see if you have the parts in your hand and think about what's going on when you tighten the screw but I didn't think about it when I had mine apart.  So if the adjustment does not seem to work right, you can measure the height of the 10-washer stack (( )) (( )) (( and add flat washers to the 9-washer stack until it's about the same height.

[Rallyshark]

Hey guys, I know a few of y'all are getting your pistols shooting up in the mid 800s to low 900s by restocking the bellievew washers, but to my knowledge most of y'all that are getting that are shooting .177 and using a reg stack like this (( )) (( )) ((. Let me know if that's right or not please. But using that same stack design with the .22 is will only achieve a high of 675fps-ish average. I've adjusted my valve spring pressure and hammer pressure quite a bit to get those results. Does anyone have any ideas on a better stack design to achieve higher set pressure.

I believe Jason is correct on this one.  I have my stack completely different, but I don't advise it, since I have 1 of the washers by itself.  That puts it at risk for flipping.  If you haven't tried it already.  Open up the hole in the valve spring adjustment nut.  That is a choke point in the system, and pretty easy to do.

[SilentMatt]

I've hit 755 with JSB .22 16gr and I've never messed with the bellevilles on mine. I drilled the valve spring retainer nut out to .1875 and shaped the front of the poppet into a bullet shape. I went about 1/3rd turn tighter from factory on my reg and adjust FPS with the hammer spring. My valve spring pressure is about one turn less than factory(I think the nut is about flush with the threads). I like it at about 700 for a good balance of shots and power.

[Ozarkairgunner]

Thanks guys, if I get a little time tomorrow I'll be trying the 9 stack that Jason suggested first, hopefully they'll work right off the bat, if it's to short I wonder about adding the 10th washer back in the stack. Either at the beginning or the end such as (((()))((( or ((()))((((, only reason being would be for the height, if I had to find a flat washer for shims where might y'all suggest for that and what size?

[SilentMatt]

McMaster has Bellevilles and shims, not sure on the thickness you'll want.

[Ozarkairgunner]

Update: well I've tried a few different arrangements on the bellievew washer stack and still not much progress, I've got some shims on order to increase my overall length on the stack, I believe my main problem is do to the fact of limited movement and the fact that I still have to have my reg adjustment bottomed out to put pressure on the stack. I was able to gain a few fps with all 10 stacked ((()))(((), but I don't like leaving the 1 by itself so I took it back out and went to my original stack (())(())(( until shims make it in, don't want to damage the washers you know.

[Wayne52]

I've looked myself too for outsourcing for the bellvue washer, basically what I'd do is measure the the bellvues that come with it and get the closest to it probably.  C.J. it will be interesting seeing the results that you get from the washers that you order.

[nervoustrigger]

CJ, do you recall how high you got the regulator with the previous Belleville arrangement?  I don't mean from having measured it directly with a gauge, just based on where the velocity began to deviate.
 
I wasn't keeping notes but I think I had mine adjusted up around 150bar (~2150psi) at one point.  So with the nested groups of 3, you would get a 50% higher spring rate which means you could expect to be able to adjust up to >3000psi and be in full bypass mode.
 
By the way, that single Belleville is surely toast now   It will have been squashed beyond flat and inverted against the adjacent group of 3 so I suggest marking it to keep it from getting mixed up with the rest and just treat it as a shim now.

[Ozarkairgunner]

Jason, no I really don't recall where it dropped exactly, I know that I was only able to gain about 10fps putting me just shy of 700fps (698 to be exact) but my SD was all over the place, mostly because of the single washer I'm assuming. ES was 24fps so not to bad there, but also lost 10 shots putting me at a 26 shot string.
The single washer in question appears to be fine, no deformation, although I suspect it's structural integrity may have been damaged. I did place it in the reg last so I'd know where it was. With everything back the way it was I seen no changes from original except my SD and ES have slightly increased, SD 5.4fps ES 17fps, which I think is mostly the reg settling back in from the washers being arranged.
I'm not sure if the "shims" are actually shims. They are small thin flat washers that I'll need to bore the center out to fit over the post.

[nervoustrigger]

Yeah, I'm not a regulator expert but I would expect the consistency to be somewhat worse with 40% less travel available in the stack (3 units of spring travel instead of 5).  I don't think it's related to the lone washer though.  It's just a pancake along for the ride
 
Regarding the loss of shot count...if memory serves you were at about 40 shots so the recent test knocked it down to about 30 with only a 10fps increase in velocity.  My best guess is it was running well up on the velocity plateau and wasting a good bit of air.  If it was noticeably louder or the report seemed longer than before, that's probably it.  Too much hammer spring preload, too much dwell.
 
On the subject of shims vs washers, the key difference is just how precise is the thickness.  For what you're doing, washers are fine.  Just deburr after drilling and smooth the flat surface with wet sandpaper against a glass backer to knock down the edge that is usually left around the rim from being punched out of sheet stock.  Again, I'm not sure the washers are absolutely necessary.  The adjustment nut may work just fine without them despite the overall stack being shorter.  But I will say this...if you can get your hands on 3 more of the Bellevilles, that would be preferable to the washers.
 

[Ozarkairgunner]

Okay after reading this yesterday and some thought I took my reg apart again and looked everything over very carefully. I still maintain that the one washer has no visible sign of damage, not saying that it's not. But I went ahead and measured everything again, making sure to write it down this time lol. The original washers are as follows OD: 8mm, ID: 4mm, Thickness .44mm

A quick call back to McMaster and I was able to catch them before my flat washers had shipped and canceled that order. Then with some help ordered a 12 pack of bellievew washers pretty dang close to the originals, part # 9712K57 and the correct shims, 50 pack part # 98055A088. More shims than I'll ever need, so if I am able to figure something out with the stack or shims I'd be more than happy to get rid of some lol.

Are you think of a stack )))((()))((( if it's not to long?

[nervoustrigger]

Yeah if you can use 15 washers in the 3P 5S arrangement, I say go for it.  That will make the stack about 0.086" taller than the original 2P 5S(the thickness of 5 washers).  I don't know if the regulator body will accommodate that much and still maintain the necessary relationships but it doesn't look like all that much.  Worst case, try the 3P 4S arrangement.
 
My guess is the higher spring rate will give you an upper limit that goes beyond the fill pressure.  We don't know what your current setpoint is but if it's much above 2000psi and you want to squeeze more out of it, before long you might want to see what you can do with bypassing the regulator and tuning it for a bell curve.  At some point the usable pressure range will just get so narrow that it isn't very useful.

[Ozarkairgunner]

Not really sure what you're meaning when you're saying 3P 5S

[SilentMatt]

I hit 775 with 16gr JSB's today. This was with the hammer spring pretty high just to see what I gained(was topping out at 755). Ended up enlarging both the valve spring retainer and TP at the barrel to .201, blocking off all the valve holes except the top(also enlarged it) and smoothed the transition in the breach block. I ended turning the hammer spring down to 680 with 16gr and 719 with 14gr. I was able to loosen the valve spring retainer until it just contacted the spring and loosen the hammer spring a considerable amount. My reg is still stock and at about 1/4 turn in from the factory setting.

[Rallyshark]

Be careful loosening that valve spring too much, or you may get an air dump if the pressure is low with the hammer leaning on the valve pin.  There isn't really that much need to loosen the valve spring much anyway, unless you're shooting at really low pressures.  At the higher pressures, the effect is minimal on the velocity and hammer spring adjustments FWIW  

[SilentMatt]

I fall off the reg around 100 bar, so that's where I stop shooting. It takes about ten shots after that and a lot of force to get the valve to dump when I'm emptying the cylinder. Didn't know there would be any danger there? Running the valve spring loose let me turn my hammer tension down quite a bit, which helps with the trigger pull and should also aid in lessening hammer bounce. I did it for efficiency and consistancy. That'll have to do until I build a balance valve for it.

I still need to get some some shot strings with the valve spring at different tensions to see if it has an effect on efficiency. I'm also not sure if changing the shape on the forward face of the poppet changes the force of the pressure acting on it, or if the force remains the same for a given diameter regardless of the angle of the face.