[brycelarson]

At the request of KC from Stiffi I shot the Stiffi TPX barrel and the stock barrel.

here's the data sheet:
http://spreadsheets....GRg&output=html

and here's the video of the test:


The Stiffi barrel weighs in at a tiny 36g and looks really cool. As has happened in every other barrel test we've done - there wasn't a statistical difference in accuracy between the barrels.

Really want to thank KC and Stiffi on this one. It's really great that a company has the balls to willingly send us stuff to beat on. It really shows that they stand behind their work. They approached us. I wish that more companies were as willing to step up in this way.

Disclaimer - the barrel used in this test will not be kept or sold by PunkWorks or anyone related to PunkWorks. It will be given away.

[PacosTacos88]

First!

Can I haz barrel?

[Pearlsea]

No I can has barrel for my awesome proposal of testing how paintballs would perform in a vacuum we will be colonizing the moon sooner then we thing and I think its a valid experiment so we know we can still shoot each other with gelatin on the moon when we have to abandon the earth in the aftermath of a nuclear world war.

Sooner then we think!

[Spitlebug]

I love the sped up footage! It's actually quite interesting to watch.

[brycelarson]

Spitlebug, on 21 September 2009 - 03:03 PM, said:

I love the sped up footage! It's actually quite interesting to watch.

do you like the part where my dog was trying to fetch the paintballs?

[Leafy]

wow thats strange how the, stock barrel is marginally better than the stiffi, of course thats within the range of error right?

[brycelarson]

Leafy, on 21 September 2009 - 03:28 PM, said:

wow thats strange how the, stock barrel is marginally better than the stiffi, of course thats within the range of error right?

Gordon can run the confidence intervals - but I don't think this is enough difference to say that one is better. Basically one winger could make this much difference.

[wilko]

brycelarson, on 21 September 2009 - 03:55 PM, said:

Leafy, on 21 September 2009 - 03:28 PM, said:

wow thats strange how the, stock barrel is marginally better than the stiffi, of course thats within the range of error right?

Gordon can run the confidence intervals - but I don't think this is enough difference to say that one is better. Basically one winger could make this much difference.

But wouldn't a larger amount of shots increase the power of the results, therefore allowing for a bigger chance of the difference between the two barrels being statistically significant?

[MondoMor]

Bryce, was this the barrel you had with the TPX on the day of the laning test?

Had I not been one digit off in the drawing for the TPX at Splat Tag yesterday, I'd be begging you for it.

[brycelarson]

wilko, on 21 September 2009 - 04:10 PM, said:

But wouldn't a larger amount of shots increase the power of the results, therefore allowing for a bigger chance of the difference between the two barrels being statistically significant?

yes, the larger the sample size the smaller the confidence interval. In the types of statistical analysis we do 20 is really a magic number. It's large enough for the number to have real meaning - while not being so large that it makes the tests unwieldy. There is a diminishing return on sample size at some point. So, yes, in a test with an infinite sample size we could know exactly how the two things compare. Obviously that's not possible - which is what the confidence interval takes into account.

Having done a ton of these tests - without running the math myself - it looks to me that the difference isn't big enough in this case to be statistically significant.

....5 minutes later.

I just did a little poking around - I'll let Gordon show his work - but it looks to me like with a sample this size there would have to be a variance of somewhere between 1.2 and 2 between standard deviations in order to say with 95% certainty that one barrel is better. We're far less than that on this test. So, no, there is no statistical significant difference in accuracy between these barrels.

MondoMor, on 21 September 2009 - 04:23 PM, said:

Bryce, was this the barrel you had with the TPX on the day of the laning test?

Had I not been one digit off in the drawing for the TPX at Splat Tag yesterday, I'd be begging you for it.

yup, this is it.

and we'll find a good reason to give it away.

[D.K.]

Bore of Stiffi TPX barrel?
Bore of Stock TPX barrel?
Average bore size of paint?

I actually was hoping(before I saw this thread) that you didn't do this test yet so you could do a decible test between carbon fiber and aluminum barrels.

[NovaPB]

D.K., on 21 September 2009 - 04:55 PM, said:

Bore of Stiffi TPX barrel?
Bore of Stock TPX barrel?
Average bore size of paint?

I actually was hoping(before I saw this thread) that you didn't do this test yet so you could do a decible test between carbon fiber and aluminum barrels.

We demand decibel testing! If they don't effect accuracy, then the only thing barrels are good for is efficiency and reducing the sound signature of the marker.

P.S. You were not wearing goggles. And neither was your dog

This post has been edited by NovaPB: 21 September 2009 - 06:13 PM

[D.K.]

I was asking because the stiffi velocity numbers were less consistent.

[brycelarson]

dunno what the barrel bores were - I talked to KC and he couldn't remember if he sent me the 691 that was their standard - or ran a 689 for me. the stock TPX is 691 I think.

paint is large - snug in a phantom breech - so should be around 687/689.

for a paint to barrel match this gun is very consistent. It's basically a modern version of a mag valve - so it's really a great valve system.

I do own a SPL meter - I'll pull it out and do some barrels at some point.

[Lord Odin]

brycelarson, on 21 September 2009 - 08:39 PM, said:

dunno what the barrel bores were - I talked to KC and he couldn't remember if he sent me the 691 that was their standard - or ran a 689 for me. the stock TPX is 691 I think.

paint is large - snug in a phantom breech - so should be around 687/689.

for a paint to barrel match this gun is very consistent. It's basically a modern version of a mag valve - so it's really a great valve system.

I do own a SPL meter - I'll pull it out and do some barrels at some point.

Wouldn't a spectrum analyzer program be better for the sound? I tried to do some SPL measuring before but everything came out the same, even though you could hear a noticeable difference in the sound.

[Leafy]

Lord Odin, on 22 September 2009 - 08:16 AM, said:

brycelarson, on 21 September 2009 - 08:39 PM, said:

dunno what the barrel bores were - I talked to KC and he couldn't remember if he sent me the 691 that was their standard - or ran a 689 for me. the stock TPX is 691 I think.

paint is large - snug in a phantom breech - so should be around 687/689.

for a paint to barrel match this gun is very consistent. It's basically a modern version of a mag valve - so it's really a great valve system.

I do own a SPL meter - I'll pull it out and do some barrels at some point.

Wouldn't a spectrum analyzer program be better for the sound? I tried to do some SPL measuring before but everything came out the same, even though you could hear a noticeable difference in the sound.

there was some reason for this that I cant remember, I think it has to do with how the spl meter works, how it reads the pressure wave and not the sound or something.

[brycelarson]

Lord Odin, on 22 September 2009 - 08:16 AM, said:

Wouldn't a spectrum analyzer program be better for the sound? I tried to do some SPL measuring before but everything came out the same, even though you could hear a noticeable difference in the sound.

I've got both. I just don't have a calibrated mic for my USB preamp. I can use the SPL meter to eyeball calibrate the computer I suppose. It won't be exact, but for our needs it should be fine. I'll look into this - sounds like a good winter project. I should be able to produce waterfall plots of volume at frequency. That would be a good descriptor of whether it's a thud or a smack sound.

[Troy]

At about 2:30 it looks like you ate one of the paintballs... thats disgusting, lol

[brycelarson]

Troy, on 22 September 2009 - 09:12 AM, said:

At about 2:30 it looks like you ate one of the paintballs... thats disgusting, lol

gotta snack on something while I'm testing.

[Spitlebug]

brycelarson, on 21 September 2009 - 03:08 PM, said:

do you like the part where my dog was trying to fetch the paintballs?

I saw that, your puppy seems like quite the character.