My problematic S410

[Missed-Em]

OK, all new seals on my AA S410, still a minor leak somewhere but I put it over the crony this am and strange results.  First the basics - FAC carbine in 22 with fill to 2750 psi per tank gauge shooting 15.8 gr pellets temp in low 30's. 

Shot     Vel        Shot     Vel
 1         728.5     11        E
 2         811.7     12        E
 3         760.4     13      813.8
 4         742.2     14      811.7
 5         767.0     15      E
 6         830.1     16      804.0
 7         E            17     799.6
 8         759.8
 9         E
 10       754.6
 
So, lots of missed readings but obviously something wrong somewhere.  Why the large discrepancies in the velocity?

Still learning here so be gentle....

 

[Avra]

Hi Missed-Em,
Give some more info about your rifle (e.g. general condition,modifications,regulated or not ecc).I am sure sooner or later more expert members will join in here and some more details of your rifle 'history' will make it a bit easier to give you directions/assistance...

[Motorhead]

Would start by shooting some other known good shooting AG over the chrony making sure it's working right

Did you polish up the stem that hammer slides on, light oil it too ?
Seal between valve body to receiver ... O-ring or the white teflon flat seal used ?
Done a tissue test making sure no leaks happening when guns fired .... Breech o-ring, above mentioned seal etc ...

We'll get it figured out 

[Avra]

In the mean time here are some ideas to start with:
(...assuming there's nothing terribly wrong with your Chrony that is...)
Check: hammer/hammer spring condition(hammer bushing,hammer rod,ecc.)
             barrel and breech seal o-rings (position/condition)
             power adjustment knob condition/friction
     

[Avra]

Oh,I just noticed Scott joined in!
You are in good hands my friend!
Dimitris 😃

[Missed-Em]

Would start by shooting some other known good shooting AG over the chrony making sure it's working right

Did you polish up the stem that hammer slides on, light oil it too ?
Seal between valve body to receiver ... O-ring or the white teflon flat seal used ?
Done a tissue test making sure no leaks happening when guns fired .... Breech o-ring, above mentioned seal etc ...

We'll get it figured out 

Thanks for the suggestions, I'll put my Disco over the crony today.  On the stem, I just cleaned it and put some grease on it (Krytox (?)), I've got a new Foster fitting coming so when I degas I'll polish it up and use oil, is pellgun oil Ok?  I replaced the Teflon seal with an O-ring, should I have used the old seal?  More leak testing after the Foster fitting replacement (suspect the current vale is a leaker).

[Missed-Em]

OK, so my crony was bonkers, fixed the lights and the S410 ran a nice 810 - 820.

Still like an answer to above questions and hope with the new fill foster valve I can put this gun in the squirrel woods.

Steve

[Avra]

Good news the trouble was in the Chrony readings and not in the rifle!
A right sized o-ring provides a viable alternative breech seal ,no problem there.
I would avoid lubrication in the hammer guiding rod though.It had costed me some inconsistency issues in the past..A good polishing is all what is needed there!

[Smoketown]

So,

How fast does she leak down?

I've used balloons to check for leaks.

One over the muzzle and one (a larger one) over the fill fitting.

Of course if the barrel is shrouded it doesn't work quite as well but, it still lets you know that you have a leak without getting your gun 'wet'.
Just be sure to put electrical tape over the ports at the breech. 

I take it that you have tried cleaning the current fill valve as they ALL get gunked up and leak sooner or later.

Cheers,
Smoketown

[Missed-Em]

Thanks for the ideas/info.  I had previously found the old fitting was leaking pretty bad so removed it, flushed with brake cleaner, dried with air compressor and crossed my fingers. seemed to work but I have no confidence in it.  The old fitting requires a 3 inch batch of fittings to fit on my tank, so wanted to convert to standard Foster fitting anyway - hope it solves the leak problem, and while degassed I'll polish up the hammer slide.

[Missed-Em]

If it ain't one thing it's another!

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So now the valve wont close.  Put air in via the new foster fitting and it comes out the barrel.  What do I look for?  Getting tired of taking this thing apart!!!!!

[LDP]

If you didnt cock it first try that. Usually on a completely empty pcp the hammer holds the valve open.

[Missed-Em]

Yep Leland, I did that - I have my suspicions, will dive into it today.