Gg Warthog 9' Upgrade / Maintenance

[Ad_]

2 hours ago, Davegolf said:

This is the reason for the heat set stretch, gives much better seal from a standstill, also excess grease blocking ports will negatively affect sealing too.

 

This is why I never use a full cylinder, the sudden ramp up in pressure a port provides allows a much more instant and consistent seal.

 

I'm not sure this will necessarily improve performance though, at least in some guns.

 

e.g. the O-ring on the piston in my P90 fits loosely in the cylinder and fails the "finger test" - if I hold the cylinder vertically and drop the piston down into it it'll just fall straight to the bottom even if I block the exit aperture on the cylinder head - there's no air seal unless it's moving quickly. However with that O-ring my P90 does a bit over 330fps on an SP90 spring.

 

If I swap the O-ring out for a more "regular sized" one such as one of the Lees Precision O-rings or take one off another piston head, that will be a much closer fit to the cylinder and will seal immediately, passing the finger test, but it will also drop the muzzle velocity to around 315fps.

 

2 hours ago, Davegolf said:

Just use this stuff on all air seal parts

 

Thanks for the suggestion I currently still have a little Marui grease left (got a small tube of that from somewhere ages ago, mostly gone now though) plus some Systema cylinder grease and I got another silicone grease from AK2M4 a while back that I plan to try out as well. At some point I'll have to test and compare them.

[Skara]

11 minutes ago, Ad_ said:

hold the cylinder vertically and drop the piston down into it it'll just fall straight to the bottom even if I block the exit aperture on the cylinder head - there's no air seal unless it's moving quickly

For the reasons mentioned above, that is not a proper air seal test.

You need to push the piston.

 

If it does 330 with a sp90 the air seal is good.

[Adolf Hamster]

Wow just seen this thread.....

 

Ptfe on the cylinder head is a functional bodge for changing the o ring (which is the preferable strategy if your trying to do things properly)

 

But not the piston head, just replace the o ring with one that seals properly.

 

As for dynamic sealing, i guess if your getting good shot-shot consistency, but personally i preferr it working static, at least that way i can test if its good or not without having to reassemble the whole thing.

[Sitting Duck]

There are numerous reasons why some piston heads are better/worse than others...

 

One of which is on many piston heads the rear of head is a tiny bit smaller than the front

meaning there is less o-ring support where it matters when compression is building on release

I don't know why this is, but good effective piston heads have less play at the rear against cylinder walls

 

Then coupled with a decent o-ring of correct size and stiffness - but still supple

(I had a very soft red silicone o-ring come out of piston and was caught up partially behind the head as piston flew back & forth)

with decent ports to assist swelling the o-ring blah blah blah etc...

 

The red soft silicone o-ring was way too soft, when fitted it sealed very snug, and created awesome compression asap

but there was some friction/drag, that even well lubed allowed it to tear itself from the piston in use

(bloody surprised to see something odd looking in cylinder port and thought WTF x 10, needing to open box (again) to replace)

a bit too soft, softer than G&G's green o-ring - yeah another no so bright idea of mine, so avoid ultra soft o-rings

 

Just go with decent std o-rings that are not too old & stiff/brittle

 

For what it is worth, I tend to use decent std stock piston heads on a steel rack piston most of the time

Cyma's & JG's are pretty good, Cyma's as they are, JG 5 holes, just widen slightly as a bit tiny

But a new or stretched o-ring on there and they work a treat - way better than G&G black piston heads

 

I've bought numerous other aftermarket heads, some were fucking dire, worse than G&G even

Coming to the conclusion, there are quite a few pretty good stock piston heads out there that only need a new o-ring

 

I also try to use if possible stock cylinder heads as I prefer plastic tbh

doubt if it matters much, but to me the transfer of impact energy is probably a whisker more on alloy to alloy

than plastic to alloy, bit like striking metal to metal or using a softer rubber mallet on delicate materials

(yeah OK plastic cylinder head is not like a rubber mallet, but some of the principle might still apply)

Just the idea of metal cylinder head transferring the energy to front of gearbox - like a jack hammer might increase potential risk of cracking over a whisker less probability of plastic cylinder head being used

Again there is probably very little difference scientifically but in my mind I tend try to re-use the stock cylinder head(s) where possible

Not a cost saving issue, well yeah it is, but there are often other reasons like how the nozzle fits on the cylinder head too

(you don't want it too tight that it struggles to move easily in operation, quite moderate in fact that is glides freely)

 

In all of this though, the various components influence what shit you use in a build at times...

Sometimes that particular super duper CNC double o-ring with rubber up front head is ideal, but don't like that nozzle

So you look to change the nozzle, but that other nozzle don't sit too well on tappet plate

So you now have the conundrum of changing the friggin' tappet too - or just use a different head instead, like stock one ???

 

Think the golden or simple rule is to change as little as possible (if possible)

as the more shit you change the more crap you have to closely check & confirm the all operate efficiently together

Hence wise advice is to just try a few other o-rings first, though on most G&G heads - yeah best of luck on that one

(People saying they got great G&G compression in 3... 2... 1... - look just saying me personally didn't get great results)

 

End of the day, we all do weird shit that we roll with, some stuff works for us, but not for others

some people might think fuck that, others will think differently and as said, we all do stuff a little differently

(what stuff works for us as said)

 

Opinions though are like arse-holes, everybody has one but don't go rubbing yours in other people's faces etc...

 

Plus above all else, I for certain am always looking to improve or change or fuck go back to basics

in other words, the shit we do is always changing, I do stuff a bit differently now to what I was doing a few years back

and no doubt will still change/adapt methods as I go along if I discover a better or more effective/efficient technique

 

Keep playing with ya toys and improving them (and our methods)

[Ad_]

8 minutes ago, Skara said:

For the reasons mentioned above, that is not a proper air seal test.

You need to push the piston.

 

That's what I'm referring to by "finger test" - pushing the piston through the cylinder while keeping a finger over the exit aperture on the cylinder head. I mangled that paragraph a bit during editing so it wasn't clear.

 

I just mentioned the gravity test to indicate how loose fitting against the cylinder my P90s O-ring is; with other more "regular size" O-rings the resistance of the O-ring against the cylinder at least slows the movement down (and due to the seal will stop movement entirely once it passes the port in the side of the cylinder).

 

Lees Precision O-rings, stock Marui & other brand O-rings, O-rings pulled off other after market piston heads etc. that I've tried in it all show the same behaviour - either they fit a bit loosely and give great compression despite failing the "push piston into the cylinder while blocking the nozzle" test, or they fit more snugly and give worse performance.

[Davegolf]

35 minutes ago, Ad_ said:

 

I'm not sure this will necessarily improve performance though, at least in some guns.

 

e.g. the O-ring on the piston in my P90 fits loosely in the cylinder and fails the "finger test" - if I hold the cylinder vertically and drop the piston down into it it'll just fall straight to the bottom even if I block the exit aperture on the cylinder head - there's no air seal unless it's moving quickly. However with that O-ring my P90 does a bit over 330fps on an SP90 spring.

 

If I swap the O-ring out for a more "regular sized" one such as one of the Lees Precision O-rings or take one off another piston head, that will be a much closer fit to the cylinder and will seal immediately, passing the finger test, but it will also drop the muzzle velocity to around 315fps.

 

 

Thanks for the suggestion I currently still have a little Marui grease left (got a small tube of that from somewhere ages ago, mostly gone now though) plus some Systema cylinder grease and I got another silicone grease from AK2M4 a while back that I plan to try out as well. At some point I'll have to test and compare them.

 

Yes so your P90 is really heavily on dynamic sealing, I would think your 15fps is possibly due to a slower accelerated BB rather than kicked up the ass, so it may have spent more time in the barrel gathering energy, or it's just a random event that if you did the same back to back test again you'd get a different result.

 

Yes that GunSav is insane slippery, the harder you squeeze it the more it slides!

 

And yeh 330 is good for a 225 barrel and 90 spring, more can be found 👀

21 minutes ago, Adolf Hamster said:

As for dynamic sealing, i guess if your getting good shot-shot consistency, but personally i preferr it working static, at least that way i can test if its good or not without having to reassemble the whole thing.

 

Just to clarify, all piston O rings work dynamically.

But a good initial static seal is needed for pressure to bite, Otherwise extreme piston speed is needed to expand the seal to a point of usefulness.

 

I know you get that @Adolf Hamster, just clarifying 😉

[Ad_]

2 hours ago, Davegolf said:

 

Yes so your P90 is really heavily on dynamic sealing, I would think your 15fps is possibly due to a slower accelerated BB rather than kicked up the ass, so it may have spent more time in the barrel gathering energy, or it's just a random event that if you did the same back to back test again you'd get a different result.

 

My P90 is over 15 years old, most of the upgrades have been in it for almost as long (some are newer, such as the Prometheus parts) and its performance has been very consistent throughout the time I've had it (and I've spent a *lot* of time on it trying to fine-tune it), so it's not just a random event.

 

Anyway, it just goes to show that just because a particular O-ring fails the usual air seal tests it doesn't mean that it's necessarily bad, and conversely just because a particular O-ring does pass the air seal tests it doesn't mean that it's ideal; it all depends on the rest of the parts in the gun and things can get pretty complicated in that regard. As Sitting Duck posted there are a lot of factors affecting performance & fitment of parts and it can be a real PITA sometimes with results not being as expected for one reason or another.

 

2 hours ago, Davegolf said:

Yes that GunSav is insane slippery, the harder you squeeze it the more it slides!

 

I think I'll get some & try it out