DEPINGER in a regulated gun .... just learned something with bottle regs

[Motorhead]

It is universally known that for a REGULATED PCP you don't require a depinger.  WELL ..... that is true with IN-TUBE regulators that stack up against the valve with a plenum tube used for spacing / making plenum volume.  The ping created by valve stops at the regulator and the balance of the air tube does not ring !!

Which brings me to an experiment while trying to chase down making my JSAR .177 slugger more quiet.  Last week made a PEEK strike tip for the hammer to eliminate that loud TINK sound upon firing. It helped but gun still fired with this odd sound that had me scratch my head with a W T F

THEN IT DAWNED ON ME     Air tube ping !!   The gun uses a Ninja type regulator that is upstream of the drop block .... Leaving, that's right an unobstructed air tube / BIG plenum ahead of valve ... DUH !!!
* Using one of these ( Slightly modified ) installed it right up against the back of valve.  That ODD PING is now gone, lost no power and now by in large the only noise is at muzzle .... Whoed-A-thunk ?

[rsterne]

As long as the passages through the depinger are large enough (as yours appear to be), no reason that should lose any power.... 

Bob

[FuzzyGrub]

It looks like a WAR cross-flow depinger.   They do work well.     I even had it in a bulldog with larger openings and fatter O-ring.   Sounds like it may come back out of the drawer whenever I finish my Brod project.   

[AlanMcD]

Very interesting.  I'm putting together a B-Rod now too with the same arrangement, so I guess I should go ahead and put a depinger in there right from the start. . .

I do have one of the JSAR depingers (interestingly, printed with glow in the dark material), but I do think I'll need to open up the passages a bit for this higher power application (since I want the full plenum to be useful).  I also will probably put it more in the middle of the plenum, rather than against the gauge block.

[Motorhead]

Very interesting.  I'm putting together a B-Rod now too with the same arrangement, so I guess I should go ahead and put a depinger in there right from the start. . .

I do have one of the JSAR depingers (interestingly, printed with glow in the dark material), but I do think I'll need to open up the passages a bit for this higher power application (since I want the full plenum to be useful).  I also will probably put it more in the middle of the plenum, rather than against the gauge block.

That "can" work mid tube ... BUT, if the venting holes are too small the pressure drop when valve opens on one side and the air on the other rapidly trying to equalize will slide the depinger towards valve irregardless.

If you have been around depingers on this type you likely made note upon disassembly there near always against the valve 

[Mr.P]

When you all talk about "depinging" are you talking about dealing with the loud metallic "pang" that seems to come from the gun (the bottle in the case of  my airforce guns)?

Is there a way to decrease that with a bottle gun?

[Motorhead]

When you all talk about "depinging" are you talking about dealing with the loud metallic "pang" that seems to come from the gun (the bottle in the case of  my airforce guns)?

Is there a way to decrease that with a bottle gun?

yes there is ... start a new thread on this specific Q and we can give you some suggestions.

[AlanMcD]

Well, I decided to put together my action and air it up last night to test everything out for function before I start working on the stock for it, and I figured that since was just a temporary test before I take it apart to mod the stock, I left out the depinger to see how it sounded.  I heard no ping without it.  I am running about 70ccs of plenum and only running at the bottom of the regulator right now (~2200 PSI), with plenty of spring on the hammer it makes a healthy low moderated boom, but no ping.

Of course that could change with different air usage, but I thought it was interesting do far.  I might pop off a few pellets (.22 cal JSB Monsters and Beasts) to see if the sound changes.  The Monsters ought to be well over 900 fps at this level, and the Beasts should be close to it too . . . .

Oh - and the poster on the ping from bottled Air Force guns: I have no experience with those guns, but I used to have a small amount of ping in my Air Ranger when it had the "flat bottomed" aluminum factory tank on it, but that went away completely when I changed to a "round bottom" CF tank for weight savings.  And of course for those that think the ping went away because the tank material changed, it is not the tank that does the ringing but the air column in the tank via standing waves . . . the tank material can have an impact on the sound, but it is not the source of the sound.

[Motorhead]

good point ....
My JSAR that did ping uses an ALUMINUM tube
My WAR rifle as well the Bottlerauder use steel tubes and don't appear to ping at all.

When the Ping became very annoying was as the tune became more efficient.  Further the parts fit and finish allowed smoother and quieter operation more the tube ping became noticeable.

[AlanMcD]

Well, I have to say I was wrong . . . I decided to check it out and see what the power level is, and it is running a bit lower than I thought it would be (no issues, as it is not tuned at all, just assembled and aired up with a guess on hammer energy for the reg pressure) and it is running about 55 FPE right now.  Still a lot, but not as high as expected.

But here is the big thing - there is a noticeable ping present.  I guess without the pellet there was probably a much different pressure drop (it has a WAR Cobra valve in it, so it matters), and now with a pellet obstructing the air flow I can hear the ping (plus with a pellet the muzzle blast is much less, but it is not there without the pellet in the breech).

The ping is much quieter than a Marauder without a depinger in it, and I don't know if it will be worth giving up the plenum space to get rid of it (I'll probably try it out and see if I lose anything from it), but the ping is there now.

I think the key to whether or not we get a ping is in how long the plenum space is - after all, the air has to resonate at an audible frequency for us to hear it . . .

[Motorhead]

We hear it when our FACE is setting along side ... DOH !
I'm also incline to think that a tubes ping can be somewhat damped if sitting in a wood stock and in good contact.  This contact such as holding a bell incorrectly deadens the chime sound it otherwise would make.

Anywho ... Thread was just a educational "NOTE" that even some regulated configuration can be made quieter if they exhibit tube ping

Alan,
The mod i did with the WAR depinger was drill the backside hole that feeds radial holes out to 1/2"
What that did was add a bit more volume between valve and depinger while also gaining a tad of overall volume reducing the Displaced area the depinger took away from the total plenum volume.

* If wanting a # on what the depinger displaces ?   using water in a small beaker of graduated cup, fill to a measured line and then drop in the depinger and see how much volume it actually displaces.  You can go as far to re-machine the wall thickness's of the depinger and make this area even less w/o effecting the depingers effectiveness.

Scott S