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#51 woodwose

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Posted 01 January 2009 - 02:36 PM

This is very nice work fellas!

I think that it is important to note that the CP barrels have a significant amount of porting - just over 4". I happen to have a 14" .685" CP barrel that I bought because it was as close to underbored as I could get in a 1 piece, and it has roughly 10 inches of unported length. The Tom Kaye Barrel article suggests that the optimal barrel length for efficiency is 8-10 inches, and that the effective length of a barrel is the length only until the porting begins. It is very cool that this test verifies this article, since this has basically become the current conventional wisdom on barrel length vs. efficiency.

Also, where do you get Grain Belt beer? Is that midwest thing?

w0se

#52 woodwose

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Posted 01 January 2009 - 02:44 PM

Another question this helps to answer is whether it is better to size an entire barrel, or just part of it (like you do with a kit). If we look at the data for the 12/.685 one piece CP vs. the 12/.685 front/back kit, I think we might have an answer that makes a lot of sense.

The 1 piece barrel is more efficient (290.25 vs. 276.95) but less consistent (5.73 vs. 4.70). This seems to validate the theory that a 2 piece barrel does most of the acceleration of the ball in the first 5 inches (or whatever the length of the back is) instead of the full 12 inches of barrel length, so therefore there is less barrel length that can act on the ball (via friction that magnifies the ireegularity of the paint) and cause variation in velocity. Do you guys agree with this?

I can't wait to see the accuracy test. I would also like to see a Palmer barrel in there since that is the only other significantly different barrel design besides 1 piece, 2 piece, and rifled. That could be test 3 - where you test the effects of barrel porting :)

w0se

#53 woodwose

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Posted 01 January 2009 - 03:22 PM

Ok, one more thing and I promise to stop spamming this thread :)

Every time I read about someone shooting +-3fps or +-5fps I wonder what they are doing that I'm not. I am very happy to see that even with an entire scuba tank and a $750 emag, you guys are getting a standard deviation of around 5 fps. That means that if you shoot 20 shots at an average speed of 280fps, roughly 19 of them will be between 270 and 290 fps (2-sigma) and one will be outside that range.

So an emag with a scuba tank - arguably an insanely consistent setup - only shoots +-10fps! Next time someone with a pump on 12ies claims +-3fps I'm going to create an animated gif of me kicking them square in the nuts! The only way you can get +- 3fps with most guns is if you only shoot 1 shot (joke).

w0se

footnote: http://en.wikipedia....ndard_deviation

Edited by woodwose, 01 January 2009 - 03:23 PM.


#54 brycelarson

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Posted 01 January 2009 - 03:24 PM

The Tom Kaye Barrel article suggests that the optimal barrel length for efficiency is 8-10 inches, and that the effective length of a barrel is the length only until the porting begins. It is very cool that this test verifies this article, since this has basically become the current conventional wisdom on barrel length vs. efficiency.

Also, where do you get Grain Belt beer? Is that midwest thing?


we've actually disproven this idea now. The CP .683 back without a front was significantly slower than with the 10" tip - and that tip has porting for nearly all of the length. This indicates that the ball is still accelerating through at least some of the ported portion of the barrel.

And yes, grainbelt is a Minnesota thing. It's a beer that was brewed in Minneapolis right across the river from downtown starting in the 1890's. In the 40's Grainbelt Premium was introduced - it changed hands a few times and went away in the 70's - but a brewery called Schells in southern Minnesota started producing it from the same recipie in 2002. This sign is a classic landmark on the river in downtown Minneapolis.

The 1 piece barrel is more efficient (290.25 vs. 276.95) but less consistent (5.73 vs. 4.70). This seems to validate the theory that a 2 piece barrel does most of the acceleration of the ball in the first 5 inches (or whatever the length of the back is) instead of the full 12 inches of barrel length, so therefore there is less barrel length that can act on the ball (via friction that magnifies the ireegularity of the paint) and cause variation in velocity. Do you guys agree with this?

I can't wait to see the accuracy test. I would also like to see a Palmer barrel in there since that is the only other significantly different barrel design besides 1 piece, 2 piece, and rifled. That could be test 3 - where you test the effects of barrel porting :)


yes, we agree that a majority - but not all - of the acceleration seems to happen in the first part of the barrel. We looked at the two piece with an underbored back this way: it gained the consistency of an overbore via the tip - but kept much of the efficiency of an underbore with the back. Sort of a best-of-both situation. Once we have the accuracy data then the decision between one and two piece may become more clear.

As to the Palmers - yeah, that would be cool to add, if anyone has one to lend for a test - we would love to give it a try. The nice thing about this test is that once we've got good baseline testing procedures set up we can get a good comparative test with a pretty small test. In other words - once we know how the barrels we have rank - we can then setup a new test, include some known barrels and add some new ones - and get a pretty good idea about how the new ones fit into the old data.

#55 cockerpunk

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Posted 01 January 2009 - 04:07 PM

Ok, one more thing and I promise to stop spamming this thread :)

Every time I read about someone shooting +-3fps or +-5fps I wonder what they are doing that I'm not. I am very happy to see that even with an entire scuba tank and a $750 emag, you guys are getting a standard deviation of around 5 fps. That means that if you shoot 20 shots at an average speed of 280fps, roughly 19 of them will be between 270 and 290 fps (2-sigma) and one will be outside that range.

So an emag with a scuba tank - arguably an insanely consistent setup - only shoots +-10fps! Next time someone with a pump on 12ies claims +-3fps I'm going to create an animated gif of me kicking them square in the nuts! The only way you can get +- 3fps with most guns is if you only shoot 1 shot (joke).

w0se

footnote: http://en.wikipedia....ndard_deviation


let it be said that we have seen numbers like an SD of 1.8 over 20 shots out of that gun before, but, as i claimed before, this gun is one of the best guns i have ever seen in my 8 or 9 years of playing over the chrono.

it was a bit cold in bryces basement, and the paint was not as good as when we saw that 1.8 SD.

regardless the gun is about as consistent as i have ever seen guns.
The ultimate truth in paintball is that the interaction between the gun and the player is far and away the largest factor in accuracy, consistency, and reliability.

And yes, Gordon is the sexiest manifestation of "to the front."


#56 brycelarson

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Posted 01 January 2009 - 05:38 PM

yup, it was about 50 - 55 degrees in my basement (great temperature for brewing beer, a little cold for scientific paintball testing :) ) and the paint was fine, but less than perfect. Last summer with the .679 freak insert and paint only a few days out of the factory we did record a 20 shot string with a SD of 1.68

bore size test

Edited by brycelarson, 01 January 2009 - 05:38 PM.


#57 Capt. Kirk

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Posted 01 January 2009 - 06:42 PM

i feel like an idiot.... but if this wasn't testing accuracy what was it testing?

yeah... the captain plays too : )

#58 Lord Odin

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Posted 01 January 2009 - 06:46 PM

i feel like an idiot.... but if this wasn't testing accuracy what was it testing?

Consistency and efficiency and the different barrel attributes such as length, 1 piece vs 2 piece, etc. The accuracy test is coming up soon.

#59 brycelarson

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Posted 01 January 2009 - 06:49 PM

i feel like an idiot.... but if this wasn't testing accuracy what was it testing?

Consistency and efficiency and the different barrel attributes such as length, 1 piece vs 2 piece, etc. The accuracy test is coming up soon.


yup, we need distance to do the accuracy test - we like 50 feet. It's enough to get some spread, but not so long that you miss the target.

#60 Capt. Kirk

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Posted 03 January 2009 - 12:09 PM

so the first test was for efficiency? then why was t run off a scuba tank?

yeah... the captain plays too : )

#61 brycelarson

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Posted 03 January 2009 - 12:11 PM

so the first test was for efficiency? then why was t run off a scuba tank?


we measured efficiency by no adjusting the gun - that way the more efficient the barrel was - the faster the chrono readings.

#62 Poe

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Posted 09 February 2010 - 09:50 AM

The Tom Kaye Barrel article suggests that the optimal barrel length for efficiency is 8-10 inches, and that the effective length of a barrel is the length only until the porting begins. It is very cool that this test verifies this article, since this has basically become the current conventional wisdom on barrel length vs. efficiency.
...


we've actually disproven this idea now. The CP .683 back without a front was significantly slower than with the 10" tip - and that tip has porting for nearly all of the length. This indicates that the ball is still accelerating through at least some of the ported portion of the barrel.

...


At the back/front junction, the CP backs appear to have female threads. Wouldn't these threads act as porting sans front? When a front is installed wouldn't this threaded area act as additional control bore? Based on CP pictures alone, the front is adding at least one and half inches of control bore. This should be enough to make up the velocity difference you are seeing.. at least based on rough GGDT calculations.

#63 brycelarson

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Posted 09 February 2010 - 09:53 AM

At the back/front junction, the CP backs appear to have female threads. Wouldn't these threads act as porting sans front? When a front is installed wouldn't this threaded area act as additional control bore? Based on CP pictures alone, the front is adding at least one and half inches of control bore. This should be enough to make up the velocity difference you are seeing.. at least based on rough GGDT calculations.


the entire front is overbored to .700-ish. It's possible - but I'm not sure. We'll have more info when we get the flasc barrels.

#64 bvdave

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Posted 09 February 2010 - 12:55 PM

thats not it at all, that 1 inch yoru speaking of isnt enough to see differences made.

for example all my testing is done with barrels "backs if you may" that are male threaded, and the extensions (think fronts) arfe female threaded, so the control bore is right to the tip of the back, so no control bore is lost due to the female threading, a 9" back also means 9" control bore and a 6.75" back means a 6.75" control bore. when the extension or front is added on with porting immidiatly, the control bore is not changed, but velocity goes up, and if you use a longer extension, velocity goes up again. heres a chart that shows what im talking about from a test I did last year thats great to show efficency and length / porting. with the setup I use you can even put 2 fronts/extensions on instead of one for more length variations (all extensions are also double threaded by design)

you see the results best with the shorter barrels, a 6.75" control bore, when added with one extension gets an efficency boost, when you add a second extension, you get another efficency boost. these extensions are completely ported also.

Posted Image

Edited by bvdave, 09 February 2010 - 12:56 PM.

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#65 Poe

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Posted 09 February 2010 - 04:21 PM

thats not it at all, that 1 inch yoru speaking of isnt enough to see differences made.

for example all my testing is done with barrels "backs if you may" that are male threaded, and the extensions (think fronts) arfe female threaded, so the control bore is right to the tip of the back, so no control bore is lost due to the female threading, a 9" back also means 9" control bore and a 6.75" back means a 6.75" control bore. when the extension or front is added on with porting immidiatly, the control bore is not changed, but velocity goes up, and if you use a longer extension, velocity goes up again. heres a chart that shows what im talking about from a test I did last year thats great to show efficency and length / porting. with the setup I use you can even put 2 fronts/extensions on instead of one for more length variations (all extensions are also double threaded by design)

you see the results best with the shorter barrels, a 6.75" control bore, when added with one extension gets an efficency boost, when you add a second extension, you get another efficency boost. these extensions are completely ported also.

Posted Image


Thank you for this new information.

My comments were directed to the Punkworks test and conclusion though. I never said porting does nothing, just that Punkworks can't conclusively say their test proves a ported barrel increases velocity since there was over an inch of unported barrel added when a front was installed. I'm eagerly awaiting a Punkworks porting test.

Just a few questions regarding your tests:
- There appears to be two sets of data for each graph, "Ported" and "Unported". I'm assuming you have some 3" extensions that are ported, some 3" extensions that are unported and the 6.75", 9" and 12" backs are all unported? I'm assuming you rechronoed the gun between these test since the "back only" velocities are different?
- What type of barrels are you using?
- Any pictures?
- Any I.D. information on the barrels or O.D. information on the paint.
- What is the distance from the end of the control bore to the first port?
- What is the porting hole size, number etc?

Thank you again for this information.

#66 cockerpunk

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Posted 09 February 2010 - 04:28 PM

we didn't say porting improved efficiency, just that adding a ported front means that the barrel does not effectively end at the porting like some had claimed. this is becuase a ported front still increased chrono speed.

we would expect that an UN-ported front would further add chrono speed. under those conditions, then porting is inefficiency.

Edited by cockerpunk, 09 February 2010 - 04:30 PM.

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And yes, Gordon is the sexiest manifestation of "to the front."


#67 brycelarson

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Posted 09 February 2010 - 04:47 PM

the barrel does not effectively end at the porting like some had claimed.


specifically you. :)

#68 cockerpunk

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Posted 09 February 2010 - 05:46 PM


the barrel does not effectively end at the porting like some had claimed.


specifically you. :)


you gotta be brave enough to challenge your own ideas in the business were in.

cheap shot!

i'll point out how many times you've been wrong and see how you feel. :lol:
The ultimate truth in paintball is that the interaction between the gun and the player is far and away the largest factor in accuracy, consistency, and reliability.

And yes, Gordon is the sexiest manifestation of "to the front."


#69 bvdave

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Posted 09 February 2010 - 10:19 PM

- There appears to be two sets of data for each graph, "Ported" and "Unported". I'm assuming you have some 3" extensions that are ported, some 3" extensions that are unported and the 6.75", 9" and 12" backs are all unported? I'm assuming you rechronoed the gun between these test since the "back only" velocities are different?
- What type of barrels are you using?
- Any pictures?
- Any I.D. information on the barrels or O.D. information on the paint.
- What is the distance from the end of the control bore to the first port?
- What is the porting hole size, number etc?


I do have ported and unported fronts, but this test was done long ago before they were avaiable. all fronts were ported. its the barrels that were ported or unported. all bore sizes were .689 and these are Flasc Paintball Barrels, below is a picture, its a terrible picture .. barrels were not clean, lighting bad with a cell phone camera.. but its the one taken when I finished the testing... COntrol bore to first port = 13mm port size is 1.5mm with 5mm spacing 4 rows of 8 ports (32 holes total) Paint used was XO Spectrum and V1 but I did not measure the paint for that particular test (I know my bad, but when I redo it with more options ill measure the paint) I plan on redoing it with 20 shots in each catigory, and more porting methods, ported unported and double ported extensions instead of standard porting. also inseatd of only using 2X 3" extensions I will also be using 5" extensions in addition to a 3"

Posted Image
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#70 brycelarson

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Posted 10 February 2010 - 11:11 AM

cheap shot!

i'll point out how many times you've been wrong and see how you feel. :lol:


best kind of shot. and I love being wrong. not at first, but it always leads to improvement in the long run.

#71 Poe

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Posted 11 February 2010 - 12:31 PM

Attachment is in reference to post #62

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#72 bvdave

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Posted 11 February 2010 - 02:23 PM

big difference between control bore and lack of porting however, just because the porting doesnt start for another inch or more doesnt mean the control bore is still in effect since your now suddenly overbored to .700 or more in most cases
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#73 Poe

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Posted 11 February 2010 - 05:14 PM

big difference between control bore and lack of porting however, just because the porting doesnt start for another inch or more doesnt mean the control bore is still in effect since your now suddenly overbored to .700 or more in most cases


Understood. That post was just for an IM reference.

bvdave your tests pretty conclusively demonstrate porting isn't the end of ball acceleration, but did you notice it also shows earlier porting (porting closer to the marker) makes your gun less efficient? Refference your 9"+3" ported data vs the 12" ported data. If the sound reduction is the same (or if the 12" was quieter) it would tell us long rows of porting are unnecessary?

#74 bvdave

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Posted 11 February 2010 - 05:17 PM

yes the earlier the porting starts the lower teh efficency is, I have actually done quite a bit of testing trying to keep efficency high while volume low with different porting methods, the further back the porting starts, the more effect it has, but the more reduction of efficency you get. the further ahead on the barrel the less effective it is at reducing noise, but also more efficent. I have found 2 holes at the front will give a better sound to efficency ratip compared to one hole in the middle


im actually thinking of doing some tests later that will involve a barrel with porting that starts with very small holes and the holes get gradually bigger as you get closer to the front to try and maximise performance and sound reduction vs efficency loss.

Edited by bvdave, 11 February 2010 - 05:19 PM.

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#75 bvdave

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Posted 11 February 2010 - 05:36 PM

As a matter of fact, I got in my new Gen2 barrels in this week and I ran a final test yesterday, ill go calculate the data and ill post it up shortly. I made the changes in the barrels due in result to the testing I did over the fall, ill have the info up shortly.

OK here we go. Now basically my goal with these Gen2 barrels was to lower volume, increases consistancy, and take as minimal loss on efficency as possible, my goal was to keep it within 2% of the prior generation of barrels or about 5-6FPS loss maximum, but if possible I wanted to keep it about the same if possible.

Heres the data from the tests completed. I was quite happy with the results, not only did I conciderably lower the volume, but I also increases consistancy and to my supprise I also have a higher average FPS so efficency was increased. which means it is very important how and where you put your porting, a hole in a barrel is not just a hole in a barrel

Posted Image

-main changes for porting, I started by slightly increasing the size of the ports, also I started the porting slightly later in the barrel, at the beginning there is now 1 "alone" hole rather then 2, and the holes are also larger, then as you get to the main section of porting there is 1 hole on its own again and then I double up the porting on 2 of the 4 rows of porting. the other 2 rows are single again.

Posted Image



so as you suggested Poe, long rows of porting are not always nessisary, the new porting in these barrels start Further along in the barrel, but still allows a lower volume.

Edited by bvdave, 11 February 2010 - 06:25 PM.

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#76 Poe

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Posted 11 February 2010 - 05:53 PM

yes the earlier the porting starts the lower teh efficency is, I have actually done quite a bit of testing trying to keep efficency high while volume low with different porting methods, the further back the porting starts, the more effect it has, but the more reduction of efficency you get. the further ahead on the barrel the less effective it is at reducing noise, but also more efficent. I have found 2 holes at the front will give a better sound to efficency ratip compared to one hole in the middle


im actually thinking of doing some tests later that will involve a barrel with porting that starts with very small holes and the holes get gradually bigger as you get closer to the front to try and maximise performance and sound reduction vs efficency loss.


If the 9"+3" ported and 12" ported barrel sets were adjusted for the same velocity output which would be louder? What about the sound levels of a 6.75" ported vs 12"+3"+3" unported adjusted to the same velocity?

I have a theory that other than allowing a shorter barrel length, porting offers no real advantage. More specifically the sound level could be reduced by increasing barrel length (increasing efficiency) instead of adding porting (reducing efficiency). Just a theory that second test might shed light on.

Thanks again for all your work.

#77 bvdave

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Posted 11 February 2010 - 06:28 PM


yes the earlier the porting starts the lower teh efficency is, I have actually done quite a bit of testing trying to keep efficency high while volume low with different porting methods, the further back the porting starts, the more effect it has, but the more reduction of efficency you get. the further ahead on the barrel the less effective it is at reducing noise, but also more efficent. I have found 2 holes at the front will give a better sound to efficency ratip compared to one hole in the middle


im actually thinking of doing some tests later that will involve a barrel with porting that starts with very small holes and the holes get gradually bigger as you get closer to the front to try and maximise performance and sound reduction vs efficency loss.


If the 9"+3" ported and 12" ported barrel sets were adjusted for the same velocity output which would be louder? What about the sound levels of a 6.75" ported vs 12"+3"+3" unported adjusted to the same velocity?

I have a theory that other than allowing a shorter barrel length, porting offers no real advantage. More specifically the sound level could be reduced by increasing barrel length (increasing efficiency) instead of adding porting (reducing efficiency). Just a theory that second test might shed light on.

Thanks again for all your work.



ill try and test some of this stuff for you tomorrow if I get the chance or this weekend and ill give you data and show you exactally what changes you get.

My hypothesis is that there is a limit, I say this because a 9" ported barrel is quieter then a 12" with the exact same porting, so longer is not always quieter, longer is normally quieter because it alows room for more porting. but ill do your test and show you the data when I get a chance.
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#78 brycelarson

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Posted 12 February 2010 - 07:07 AM

bvdave - just as a general rule - increase your sample size. with samples that small it's much harder to tell you if what you're finding is significant. 20 is a great starting point.

#79 bvdave

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Posted 12 February 2010 - 11:21 AM

I did another test today now that I had some extra time on my hands and used a sample size of 30. I think the test shows pretty clear that there is such thing as optimal porting styles and it doesnt have to start earlier to be quieter and a hole is not just a hole in the barrel as placement is very important.

Test also shows the difference between 9" and 12" barrels. barrels are expect same other then length, 9" gen1 barrel has the exact same porting as the 12" gen1 barrel and the same goes with gen2

I am glad I did it again with larger numbers, results are much more clear now, while sound is definantly dampened and efficency definantly increased, consistancy is not what I was hoping for, it is still slightly better in both sets of barrels but its be such a small number this time its mostly irrelevant, but the reduced volume and increased efficency is still more then enough of an improvement for me. I am sure im far from the "perfect balance" of porting style lentht hole size etc etc, but its nice to know im at least getting close with all the testing done

Posted Image


In case anyone is curious about my testing setup

the Marker I use is my TM-7, it is clamped down very well and I have attached a laser to it which is tuned to the shooting box so I see exactally where each ball will hit. since its only 17 feet away its literally ball on ball as there isnt enough room for any noticable spread. I use a big red Chrono and the Sound meter is 3 feet away from the end of a 12" barrel tip on the marker. I normally run from a scuba tank but all 4 are empty right now so I did todays tests off my 110/4500 tank instead, I have 2 4500PSI nitrogen bottles but didnt feel like hauling one over :S the tank was full so it shouldnt matter too much expecially on a large tank, but normally I try and use scuba tanks because the volume is so much higher the pressure is much more consistant during testing compared to a tank that may start at 3000PSI and end testing at 1700 PSI which can give slightly different results then full. with a scuba if I start at 3000 PSI im likely to end at 2900 PSI or close

the shooting box I made myself, I use paintball neeting left over from when I ran a field up until last year to make it, the ball goes through a few dropped sheets of netting and breaks past them on a padded board, theres very little "splat" that makes it outside the box so clean up is minimal, there is 2 layers of skirts that direct all paintballs and dripping paint / shell into a large box underneath with a plastic bag in it to prevent leakage. The duck is there because he likes to live on the edge

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Edited by bvdave, 12 February 2010 - 02:36 PM.

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#80 ktap

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Posted 13 February 2010 - 12:31 PM

Why didn't you calculate the SD for sound?

Just for sound comparisons sake could you do a test with a heavily ported barrel like a SP Linear (most similar barrel to Flasc barrels that i could think of) or something similar. I think it would be interesting to see if it has any impact.

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#81 bvdave

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Posted 13 February 2010 - 01:12 PM

That test was allready done actually, only 5 shots each to give a general idea, ima buy a new sound meter bryce recommended assuming I can find one in Canada and redo it with 20 shots each in the next week or two however and ill post the new results then

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UNported = unported
Standard porting = 4 rows 3" long
Double porting = 8 rows 3" long
SQB is 8 rows 3 inches long, plus 4 of the 8 rows extends to 6 inches long.
Middle is 4 rows of porting 3 inches long starting iin the front middle of the barrel (so if you section the barrel into sections its the 50%-75% lengthso think of each = as a inch ======PPP=== so not entirly middle but front middle.

gen2 barrels were not part of the origional test but wil be part of the next test. for more sound info theres a thread in the punkworks main forum where I had a few of the sound tests ive done posted up. all of them will be redone when I get a new sound meter I can hook to the computer directly however

Edited by bvdave, 13 February 2010 - 01:21 PM.

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#82 cockerpunk

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Posted 13 February 2010 - 01:21 PM

how far away was the meter?
The ultimate truth in paintball is that the interaction between the gun and the player is far and away the largest factor in accuracy, consistency, and reliability.

And yes, Gordon is the sexiest manifestation of "to the front."


#83 bvdave

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Posted 13 February 2010 - 02:46 PM

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