[drg]

Well I tried the experiment today and failed. Maybe it's because I used the cornstarch type? Anyway firing the ball just blew out all the powder and I could not see any pattern. It was a Lapco barrel though so maybe the finish sloughed off all the powder.

[Snipez4664]

Not sure, but thats for trying

Gordon I don't think it tells us anything either but I wanted attention

[brycelarson]

drg, on 14 April 2012 - 07:27 PM, said:

Well I tried the experiment today and failed. Maybe it's because I used the cornstarch type? Anyway firing the ball just blew out all the powder and I could not see any pattern. It was a Lapco barrel though so maybe the finish sloughed off all the powder.

I've done it with flour in the past. Most of the powder leaves - yes, but you'll end up with slightly more clean portions where the ball landed.

[drg]

There was no discernible powder in the barrel after the shot...

[Jack Wood]

Humidity or condensation may play a part in how well the powder adheres to the inside of the barrel. How about breathing through the barrel first and then pouring the powder through?

Regarding bounce initiation, we can see it clearly when using a poppet based gun. I haven't revealed the cause of the initial instability so far. I was hoping someone would try and work it out

Jack

[cockerpunk]

Jack Wood, on 16 April 2012 - 12:02 PM, said:

Humidity or condensation may play a part in how well the powder adheres to the inside of the barrel. How about breathing through the barrel first and then pouring the powder through?

Regarding bounce initiation, we can see it clearly when using a poppet based gun. I haven't revealed the cause of the initial instability so far. I was hoping someone would try and work it out

Jack

its got to be either differential in power pulse pressure, or non centering of the ball in the breach/loading.

or both?

loading/non centering would probably lead to even spool valves doing it, which i dont think is the case.

means its got to be a differential in power pulse pressure.

This post has been edited by cockerpunk: 16 April 2012 - 12:32 PM

[Troy]

I was thinking about, possibly, using a towel to build up an electrostatic charge as well.

Btw, do we know if the vertical orientation of the marker effects it or not? If it does effect it, it would lend confirmation to a non centering loading problem like CP said, if it doesn't effect it, it would be pretty strong evidence that it is probably an air flow related issue.

I think it would be interesting to see if a marker's detents effect the barrel bounce also.

This post has been edited by Troy: 16 April 2012 - 01:48 PM

[mr.satire]

cockerpunk, on 16 April 2012 - 12:31 PM, said:

Jack Wood, on 16 April 2012 - 12:02 PM, said:

Humidity or condensation may play a part in how well the powder adheres to the inside of the barrel. How about breathing through the barrel first and then pouring the powder through?

Regarding bounce initiation, we can see it clearly when using a poppet based gun. I haven't revealed the cause of the initial instability so far. I was hoping someone would try and work it out

Jack

its got to be either differential in power pulse pressure, or non centering of the ball in the breach/loading.

or both?

loading/non centering would probably lead to even spool valves doing it, which i dont think is the case.

means its got to be a differential in power pulse pressure.

Gordon when you did your CFD modeling of the bolt system, did you include a "venturi" face or was it just an open bolt? Im wondering if that could affect the way the power pulse flows

[cockerpunk]

mr.satire, on 16 April 2012 - 08:22 PM, said:

cockerpunk, on 16 April 2012 - 12:31 PM, said:

Jack Wood, on 16 April 2012 - 12:02 PM, said:

Humidity or condensation may play a part in how well the powder adheres to the inside of the barrel. How about breathing through the barrel first and then pouring the powder through?

Regarding bounce initiation, we can see it clearly when using a poppet based gun. I haven't revealed the cause of the initial instability so far. I was hoping someone would try and work it out

Jack

its got to be either differential in power pulse pressure, or non centering of the ball in the breach/loading.

or both?

loading/non centering would probably lead to even spool valves doing it, which i dont think is the case.

means its got to be a differential in power pulse pressure.

Gordon when you did your CFD modeling of the bolt system, did you include a "venturi" face or was it just an open bolt? Im wondering if that could affect the way the power pulse flows

IIRC i did. i should look that up, its got to be in the experiment vault somewhere.

[Jack Wood]

cockerpunk, on 16 April 2012 - 12:31 PM, said:

Jack Wood, on 16 April 2012 - 12:02 PM, said:

Humidity or condensation may play a part in how well the powder adheres to the inside of the barrel. How about breathing through the barrel first and then pouring the powder through?

Regarding bounce initiation, we can see it clearly when using a poppet based gun. I haven't revealed the cause of the initial instability so far. I was hoping someone would try and work it out

Jack

its got to be either differential in power pulse pressure, or non centering of the ball in the breach/loading.

or both?

loading/non centering would probably lead to even spool valves doing it, which i dont think is the case.

means its got to be a differential in power pulse pressure.

Remember when I showed you the very first HSV footage all those years ago? Remember the "negative" kick we saw? Well a cup faced bolt that is pushing a ball into the barrel on a poppet gun undergoes the same phenomena. Where does a bolt pivot around when the rammer strikes the poppet valve? What would the resultant be when that happens?

It's easy to assume that the bolt has only one degree of freedom as it cycles, but that would be incorrect.

[mr.satire]

Jack Wood, on 17 April 2012 - 04:37 AM, said:

cockerpunk, on 16 April 2012 - 12:31 PM, said:

Jack Wood, on 16 April 2012 - 12:02 PM, said:

Humidity or condensation may play a part in how well the powder adheres to the inside of the barrel. How about breathing through the barrel first and then pouring the powder through?

Regarding bounce initiation, we can see it clearly when using a poppet based gun. I haven't revealed the cause of the initial instability so far. I was hoping someone would try and work it out

Jack

its got to be either differential in power pulse pressure, or non centering of the ball in the breach/loading.

or both?

loading/non centering would probably lead to even spool valves doing it, which i dont think is the case.

means its got to be a differential in power pulse pressure.

Remember when I showed you the very first HSV footage all those years ago? Remember the "negative" kick we saw? Well a cup faced bolt that is pushing a ball into the barrel on a poppet gun undergoes the same phenomena. Where does a bolt pivot around when the rammer strikes the poppet valve? What would the resultant be when that happens?

It's easy to assume that the bolt has only one degree of freedom as it cycles, but that would be incorrect.

The pivot would be at the point where the valve stem, contacts the rammer. The result would be a force on the bolt that would cause the tip to dip downwards slightly.


I really cant think of any other way to word it wich is sad considering im an ME student

[rntlee]

That's interesting, but wouldn't TK have been testing with Mags?

[Troy]

mr.satire, on 17 April 2012 - 10:35 PM, said:

The pivot would be at the point where the valve stem, contacts the rammer. The result would be a force on the bolt that would cause the tip to dip downwards slightly.


I really cant think of any other way to word it wich is sad considering im an ME student

I'm pretty sure Jack knows where the pivot is, and was just asking the question as a rhetorical device.

I'm going to test my AKA (as soon as it gets back from destructive customs) verses my only spool, a PM6. It's pretty conventional wisdom that AKA's were built with really high tolerances, and I'm wondering if that would effect how much (I'm going to coin a new phrase here) bolt dive it would have. Furthermore, because the hammer is off center, it would probably make a different looking pattern in the barrel.

[Jack Wood]

rntlee, on 18 April 2012 - 05:49 AM, said:

That's interesting, but wouldn't TK have been testing with Mags?

And where did Tom say he saw the bounces?

[Troy]

I'm going to hurt someone if we don't get a nelson based marker tested.

[cockerpunk]

Jack Wood, on 17 April 2012 - 04:37 AM, said:

cockerpunk, on 16 April 2012 - 12:31 PM, said:

Jack Wood, on 16 April 2012 - 12:02 PM, said:

Humidity or condensation may play a part in how well the powder adheres to the inside of the barrel. How about breathing through the barrel first and then pouring the powder through?

Regarding bounce initiation, we can see it clearly when using a poppet based gun. I haven't revealed the cause of the initial instability so far. I was hoping someone would try and work it out

Jack

its got to be either differential in power pulse pressure, or non centering of the ball in the breach/loading.

or both?

loading/non centering would probably lead to even spool valves doing it, which i dont think is the case.

means its got to be a differential in power pulse pressure.

Remember when I showed you the very first HSV footage all those years ago? Remember the "negative" kick we saw? Well a cup faced bolt that is pushing a ball into the barrel on a poppet gun undergoes the same phenomena. Where does a bolt pivot around when the rammer strikes the poppet valve? What would the resultant be when that happens?

It's easy to assume that the bolt has only one degree of freedom as it cycles, but that would be incorrect.

ah, you are implying that the bolt itself rotates about the hammer/valve stem point which directs air at an angle .... mmmmm. so can you possible manipulate that with the fit and length of the bolt? that would be the test there.

so why then would we see bouncing on a gun like the AXE that lurker sees? that screams airflow to me, that the AXE volume near the poppet isn't enough, and it taps into the gas transfer tube in the frame, which gives it a pressure differential across the bolt face, and thus a bounce.

[Troy]

cockerpunk, on 18 April 2012 - 08:45 AM, said:

so why then would we see bouncing on a gun like the AXE that lurker sees? that screams airflow to me, that the AXE volume near the poppet isn't enough, and it taps into the gas transfer tube in the frame, which gives it a pressure differential across the bolt face, and thus a bounce.

Could we test a bolt with an open face verses something like a cooper t bolt or alien sweep bolt and see if there are any differences?

[Snipez4664]

I don't know no one seems very interested in actually testing this

don't you guys own paintball guns?

we're trying to build a data set here

[y0da900]

It's the baby powder that's stopping me. I'll try and remember to get some on the way home from work tomorrow. I'll run a test with 4 or 5 guns - both open and closed bolt of both poppets and spools. Removing the moment caused from the eccentrically loaded moving bolt during the poppet impact using a closed bolt poppet should be a pretty good indicator whether or not that or the airflow is the cause - also removes detents from the equation, which is easy enough to double check by single loading balls into an open bolt with detents removed.

[Troy]

My primary is in the shop, and the noid on my only backup just went bad... anyone know where you can get a noid for a PM6 ?

Anyways, some alternative materials that I thought of, because like y0da900 I don't have baby powder:
1) flour
2) Bisquick
3) vegetable oil or nonstick cooking spray (especially if you can spray it down the barrel)