Dry Fire Efficiency Test

[cockerpunk]

http://www.youtube.com/watch?v=XSf_sdNygHM

[brycelarson]

link to data (http://spreadsheets.google.com/pub?key=pp1UimQwRsMmpEgg52Xdwbg)

fun little test - hope it's helpful.

[GoatBoy]

Nice, thanks for doing one using the e-mag and level 10. Also, neat use of Google Docs.



A note on measurements... There might be an alternative way to measure the air consumption without the need for an expensive, large gauge -- weigh the tank (tare it all with the gun included perhaps). This might actually be even more accurate than what you're currently using, especially with a digital scale set to grams or less.

[sffudapparel]

Cp and bryce - I hate you both.

I'm trying to study for my exam tomorrow and you post a new video so of course I had to check out the whole series of the old guns while I was at it. It's now 1:32am and I'm not even half way through the chapters i need. ;)

Keep up the good work fellas. I really enjoy it. And cockerpunk, thanks for turning the light on on the emag vid :headbang: I love that blue - wine anno

[jackwood]

Very interesting.

So now that it has shown that dry firing cannot replicate real firing with all types of guns, is that the end of this test?

Are you going to conclude that because that Ion gave identical figures with and without paint that an all Ions set up in any configuration will always give that same result, or are you going to alter some parameters (Dwell) to see if the same holds true for other set ups?

[brycelarson]

Very interesting.

So now that it has shown that dry firing cannot replicate real firing with all types of guns, is that the end of this test?

Are you going to conclude that because that Ion gave identical figures with and without paint that an all Ions set up in any configuration will always give that same result, or are you going to alter some parameters (Dwell) to see if the same holds true for other set ups?

My thought would be that the bolt design may do more than the dwell. This ION has only external upgrades. Stock bolt, un-altered factory settings on the electronics - the only thing I've done to it was a new trigger and clamping feed neck.

We have not talked about future testing. Our rig is really easy to replicate - It may be easier to ask other people to test their marker - rather than us trying to create multiple configurations of our markers.

Just looking at the mag for example covering the bases would require us to to a classic valve, RT valve, X valve then do all of those in combination with the level 7 and the level 10 to test most common permutations. The Ion would be nearly limitless with the bolt and dwell settings available.

[jackwood]

Could I suggest that you try the Ion with, say a 4ms increase in the dwell?

My thought is that the dwell setting that you have the gun set to is virtually "perfect" or even slightly under-dwelled.

In the "perfect" state, the dwell is expiring and the pneumatic system swtiching at exactly the same moment that blow-back is occuring. Thus with or without paint the readings would be the same.

In an "Under-dwelled" state, the controlling factor of the bolt retraction/dump-chamber evacuation period/level is soley the dwell. Increasing the dwell should yield a noticable increase in velocity.

The 4ms is just a plucked-from-the-air nominal figure that should tell you whether a) the Ion was operating in one of the above conditions (but not which one) or b) the Ion really does function as shown with the first data set.

Jack

[Hilltop Customs]

I'm missing what your trying to disprove or prove here......

disprove that dryfiring uses the same amt of air as firing w balls?
prove that there is a high variability between markers when it comes to the efficiency w ball and w/o ball?

oh and your graph is labeled wrong in your data sheet. "% of dry fire shots when shooting paint" should be something like "ratio of loaded vs unloaded shots using equivalent amounts of compressed air"

The question mike posed was basically "if a marker is chronoed @ 300fps, and you shoot a string of air @ 13bps for 100 seconds, is it possible to say the marker is possible of getting 1300 shots per tank?"

Only way this could be wrong is if firing a paintball forces the marker to use more gas than dry firing....which is not possible in these markers(and also shown in your data), so simple answer is "if you get 100 seconds of dryfire @ 13cps with absolutely no change to the marker after chronoing, then yes the marker should be capable of 1300ball per fill."

One catch though, some markers still fully cycle well under the pressure they require to fire a ball @ 300fps, simple solution is at the end of the 100seconds, drop a ball in the breech and fire it over the chrono and see if it is @300fps.

Another catch is if a marker doesnt fully recharge at 13cps, therefore using less gas at a higher ROF, in which case you could get more cycles than spaced out single shots.

no ball in the barrel=less restriction of gas flow out the barrel=more efficient emptying of the dump chamber=more gas used per shot

the ion is just a freak. It would be interesting to see what an increase in input pressure and and lowering of the dwell would do there. I would think it would make the ratio increase over 100% since you are cutting the supply off quicker.....might be a problem getting up to 300 fps though.

[cockerpunk]

thanks for the input jack!

my data, and what you and i have been talking about over on PBN seems to corilate well.

[Hilltop Customs]

how is it equivalent amounts of air?

clearly its not the equivalent amounts of air..


I thought you were counting shots from 2000psi down to 1000 psi......if so, the number of shots are varying not the amt of air.

edit: i'm not saying theres anything wrong with the data, graph or any of your research.....its just not an appropriate label

PS: I love what you guys doing here. Cant wait to see the break test.

[brycelarson]

Sure, the semantics of the title of the graph may not be perfect - but I think it communicates what we're trying to display. Maybe the title should read:

"number of cycles with paint devided by number of cycles without paint displayed as a percentage"

We tested to see if a gun cycling with paint could acheive the same number of cycles with a given volume of air as the same gun cycling without paint. That's what we were testing - which is actually what Mike was asking.

There are always other factors we don't include in a test (shootdown, reg recharge rate etc). There will always be factors that we choose not to incorporate and factors that we cannot incorporate. We choos the factors that we think have the highest impact on the results and then control for those. In this case that was starting and ending pressure, starting temperature, and velocity of the paintball. Those factors give us an accurate picture of how each gun performs with and without paint.

thanks for the encouraging words - we'll keep trying, and please, any suggestions are great - keep making them. Whatever we can do to improve these tests - we're willing to consider.

[dark blade]

i think what cocker punk meant is that there was varying amounts of air used in each shot when comparing dry cycles to paint cycles. not the total amount of air because yes they were doing the test with 1000 psi as a set destination for the tank

[Hilltop Customs]

Bryce I understand completely where you are coming from, there are a lot of variables, and limiting them is very difficult. I was impressed you even used water to negate the temp change off filling and emptying the tanks.

The only thing I'm trying to get at by mentioning that title of the chart is: The title of a chart should be self explanatory, anyone should be able to read the title and know exactly what they are looking at. "% dry fire shots while shooting paint" is not a good title because it is broad(no mention of same amt of gas) and confusing(dry firing while shooting paint?). Now thats not to say it is not understandable, I could understand the title after looking at the included data, but that is not why a chart is there, it is to simplify for easier understanding by the audience(ie audience does not need to look at the included data to understand the conclusion).

I know you guys dont care about being professional, but the change of those few words would make your presentation of data so much more effective. I'm just trying to help you.

edit: that last part about not caring about being professional wasnt a knock on you....i understand why it's not high on your list, because your audience doesnt care if you act highly professional. I dont want you to think i'm trying to put you down in any way, but the one great thing about presenting in a professional manner, many times it is the most effective means of presenting something(even to an unprofessional audience)

[jackwood]

thanks for the input jack!

my data, and what you and i have been talking about over on PBN seems to corilate well.

:clap: Yay, I'm not a complete idiot!! :clap:

[cockerpunk]

:clap: Yay, I'm not a complete idiot!! :clap:

i personally found the autococker to be the most interesting gun we shot.

have you ever tested a cocker on your little rig? if you dont want to make it public, toss me a PM.



also, thanks, i edited my post becuase i realized i was misunderstanding what hilltop was saying. we are all on the same page now ... i think.

[brycelarson]

The 4ms is just a plucked-from-the-air nominal figure that should tell you whether a) the Ion was operating in one of the above conditions (but not which one) or b) the Ion really does function as shown with the first data set.


We're looking at doing the barrel break test this Sunday. We'll see how long that takes and if we decide we're up for it I'm sure we could do a few additional trials with the Ion - maybe 2 sets, one at +4ms one at +8 - see what happens. Quite honestly - give me a mechanical gun and I'll make it sing, hand me an electronic one and I'm more likley to just turn it on and play with it - I don't tend to monkey with them as I don't often see as dramatic results as I would tuning a cocker (for example).

Any additional suggestions from knowledgeable people about how we could make this test cover more guns / setups etc would be appreciated.

Personally, I'm curious about a lv 7 bolt on a mag - vs the lv 10.

[Hilltop Customs]

It sounds like you want to go broad...aka formulate something that can be applied to all pb-guns in general. Only way to do that is test a wide variety of guns, and then formulate a theory thats applicable to all the data youve collected.

Mine which I posted eariler was:
no ball in the barrel=less restriction of gas flow out the barrel=more efficient emptying of the dump chamber=more gas used per shot

the Ion seems to go against that idea, which is still amazing to me...but I think its explainable by the non-sealed dump chamber. If the dwell for the ion is longer than the time it requires for the ball to escape the barrel, the the gas usage for firing a ball could possibly be equivalent to that used when dry firing.(I could explain relating it to a mag and its sealed chamber design, but that might take a little while)



You know what I would be interested to see.....if you find your # of shots dryfired and fired with with balls stock, then make a change (board settings, bolt...anything) if the % increase of dryfired shots correlates with the % increase in ball fired shots. That way you could simply empty a tank dry firing before and after a change to figure the increase or decrease of usable paintballs.

once again I would like to :clap: :clap: :clap: you guys on your work (applaud)

[brycelarson]

It sounds like you want to go broad...aka formulate something that can be applied to all pb-guns in general.

Neither of us thinks we're going to find anything that will apply to all guns - there are simply too many variations out there.

We were hoping to cover most of the main types of firing systems.

[brycelarson]

funny stuff - a thread nearly identical to this one (with a significantly lower average IQ of replies) has been closed over on PBN for inappropriate content.

I apologize if this content has offended anyone :D

[Hilltop Customs]

any chance of getting a link? it would be funny to see, but I dont really wanna have to sift through....well you know what most of the threads over there are.

[brycelarson]

it apparently was because the title of our video was "TechPB Dry Fire Efficiency Test"

the thread itself is gone - but the conversations about it are in the ask the mods section.

[cockerpunk]

here is the PBN link - http://www.pbnation.com/showthread.php?t=2809760

fun stuff, PBN is worst about this crap.

[SCpoloRicker]

Just read your exchange at PBN.

All I would say to you is:

"Your a idiot"

[Beemer]

Just read your exchange at PBN.

All I would say to you is:

"Your a idiot"

All I would say to you is see ya next week. Thats what ya get for flaming. You come back and I have to Mod another one of your posts you WILL get a perm. Come On you know better. :nono:

[cockerpunk]

thank you!

im currently uploading the "PBN safe" version of the test.

[cockerpunk]

PBN version, thought you guys might like it - http://www.youtube.com/watch?v=ct5fmfl4Oxk

[sffudapparel]

pbn sucks.

keep it up like always

[GoatBoy]

Boyle's law is:

P1*V1 = P2*V2

Assume LHS is the tank, RHS is basically STP.

1000PSI * 13ci = (14.6959488 PSI)*V2

884.59752935448455 ci of air consumed in your test.

884.59752935448455/(12*12*12) = 0.51191986652458599 cf

The weight of air is around 0.0807lbs/cf.

0.51191986652458599cf * 0.0807lbs/cf = 0.041311933228534083 lbs.

0.041311933228534083 * 16 * 28.3495231 = 18.738777685887751g

Taking your data for the Emag with level 10:

0.33462103010513838grams per shot, roughly.

I just did a quick trial with my mag (X-valve, level 10, 5 shims, gold spring), dry firing only (can't shoot paint). I didn't have enough air to do 100 shots, so the accuracy is suspect, and but I threw the mag on a scale and recorded the weight. It started at 2080grams, and after 40 shots, it was at 2070 grams, so roughly about 0.25grams per shot.

There's still a lot of variables here (my data's pretty suspect because it's unchrono'd and I didn't take enough shots), but someone with more air might want to see how repeatable this is.

[cockerpunk]

Boyle's law is:

P1*V1 = P2*V2

Assume LHS is the tank, RHS is basically STP.

3000PSI * 13ci = (14.6959488 PSI)*V2

V2 = 2653.7925880634534 ci

2000PSI * 13ci = (14.6959488 PSI)*V2

V2 = 1769.1950587089689 ci

Subtract the two, you get:

884.59752935448455 ci of air consumed in your test.

884.59752935448455/(12*12*12) = 0.51191986652458599 cf

The weight of air is around 0.0807lbs/cf.

0.51191986652458599cf * 0.0807lbs/cf = 0.041311933228534083 lbs.

0.041311933228534083 * 16 * 28.3495231 = 18.738777685887751g

Taking your data for the Emag with level 10:

0.33462103010513838grams per shot, roughly.

I just did a quick trial with my mag (X-valve, level 10, 5 shims, gold spring), dry firing only (can't shoot paint). I didn't have enough air to do 100 shots, so the accuracy is suspect, and but I threw the mag on a scale and recorded the weight. It started at 2080grams, and after 40 shots, it was at 2070 grams, so roughly about 0.25grams per shot.

There's still a lot of variables here (my data's pretty suspect because it's unchrono'd and I didn't take enough shots), but someone with more air might want to see how repeatable this is.

it was 2k psi

[GoatBoy]

it was 2k psi

Oops. Oh well, it doesn't really matter (it might if we have to start accounting for nonlinearities due to pressure). What matters is you dropped 1k worth of PSI at roughly 13ci. You can actually simplify the math a lot if you sit down and solve the equations.


Again, I think a digital scale is cheaper, easier to obtain, easier to use (install), and easier to read than an analog PSI gauge. Also, the size of the tank shouldn't matter much, so people don't have to buy 13ci tanks to try it on their own. It's something to think about if you want a lot of other people doing testing as well.

[jackwood]

Gordon, what do you find surprising about the cocker?

Did you expect it to be better or worse? (More shots with paint than air, or the same number of shots with paint and air?)

The cocker is probably more complicated than the other guns because LPR pressure and "Trigger Pull Rate" (for want of a better term) can all have an effect on the both bolt retraction points, times and rates as well as the bolts ability to resist blow-back.

The "Trigger Pull Rate" will vary massively from shot-to-shot compared to either an electro or the Mag.

Add to that the fact that varying roll-forward of the ball in the barrel on a cocker will also produce varying amounts of blow-back, and it all starts to look very messy.

The last time I plugged a pressure transducer into a cocker valve chamber was probably in early 2001, and I for sure don't have either that data to hand. We didn't tool at this specific problem, so I didn't do with and without paint comparisons of that, either.

ION: Hilltop may have a point. A vastly over-dwelled situation may also, in theory, produce those figures. Even if the bolt is blown back and re-seals the dump chamber buring the ball fire before the dump is empty, if the bolt return air is not re-introduced to coincide with that, then the bolt could pop forward after the ball has been fired and dump the remaining air in the chamber/set up a mild free-flow state (the Ion restricts flow of inlet air to the dump chamber, but does not produce an perfect seal/block).

Jack

[brycelarson]

ION: Hilltop may have a point. A vastly over-dwelled situation may also, in theory, produce those figures. Even if the bolt is blown back and re-seals the dump chamber buring the ball fire before the dump is empty, if the bolt return air is not re-introduced to coincide with that, then the bolt could pop forward after the ball has been fired and dump the remaining air in the chamber/set up a mild free-flow state (the Ion restricts flow of inlet air to the dump chamber, but does not produce an perfect seal/block).

Jack

As I said before - I tend to just leave my electro markers alone - quite honestly, while the perform great the creep me out a bit.

Anyone know what the stock ION dwell time is on the original gun?

Based on people that better understand the potential cycle times of an ION - is that dwell time likely to be severely under or over the optimal dwell time?

[cockerpunk]

Gordon, what do you find surprising about the cocker?

Did you expect it to be better or worse? (More shots with paint than air, or the same number of shots with paint and air?)

The cocker is probably more complicated than the other guns because LPR pressure and "Trigger Pull Rate" (for want of a better term) can all have an effect on the both bolt retraction points, times and rates as well as the bolts ability to resist blow-back.

The "Trigger Pull Rate" will vary massively from shot-to-shot compared to either an electro or the Mag.

Add to that the fact that varying roll-forward of the ball in the barrel on a cocker will also produce varying amounts of blow-back, and it all starts to look very messy.

The last time I plugged a pressure transducer into a cocker valve chamber was probably in early 2001, and I for sure don't have either that data to hand. We didn't tool at this specific problem, so I didn't do with and without paint comparisons of that, either.

ION: Hilltop may have a point. A vastly over-dwelled situation may also, in theory, produce those figures. Even if the bolt is blown back and re-seals the dump chamber buring the ball fire before the dump is empty, if the bolt return air is not re-introduced to coincide with that, then the bolt could pop forward after the ball has been fired and dump the remaining air in the chamber/set up a mild free-flow state (the Ion restricts flow of inlet air to the dump chamber, but does not produce an perfect seal/block).

Jack

ill post my theroys after the discussion boils down to something.

one thing i have learned though this all is to keep my damn mouth shut until someone says what i was going to say.

as far as the trigger pull rate, i was as careful as i could be to get a very rythmic pattern going, becuase i also suspected the mechanical timming issues with the cocker would lead to diffrences. we did our best to keep the trigger speeds identical, with all the guns.

[Hilltop Customs]

after thinking about it a little more....the ion using the same amt of air dry firing and with a ball makes some sense if the dump chamber pressure never drops below the residual pressure level(behind the ball as the bolt comes back to a close) because of the unsealed dump chamber design.

immediately after the bolt starts moving forward ion you there is a pressure drop, and the air begins to flow from the reg to the dump chamber....this doesnt stop until the bolt resets and the dump chamber pressure re-equalizes with the reg'd air. Although there is a restriction in flow, I think enough air gets through while the bolt is in motion to keep the dump chamber pressure above the residual pressure, thereby keeping a flow out of the barrel until dwell closes the bolt.

Now if you look at something like the mag on the other hand, the dump chamber is sealed so once you hit a certain pressure difference (in the barrel and in the powertube) the bolt spring applies enough force to push the bolt back, sealing in residual pressure. Now if there is no ball in the barrel, the forces(internal, external and spring) will take longer to equalize....making a mag in essence have a longer dwell when there is no ball in the breech.
longer dwell=more air escapes=lower dump chamber pressure after a dryfire= more air required to fill the dump chamber than a ball fired shot


hopefully that makes sense

[Beemer]

here is the PBN link - http://www.pbnation.com/showthread.php?t=2809760

fun stuff, PBN is worst about this crap.

Was the original thread there removed?? You can post and refer to Tech PB here. Just dont POST ANY LINKS to his or your vids with SWEARING. That guy has a bad potty mouth that is not AOs style.

edit.... Oh ya on a side note and not to be rude but who cares about paint or no paint and air cunsumption? I know I dont.

What I REALLY CARE about is consistency. Get the FPS on every ball at what ever ROF.

At one BPS I have a gun I can get 299, 299, 299, FPS on CO2. Now what will it be at five, ten or fifteen BPS????? Who can chrono EVERY ball at ten or fifteen BPS? Thats FPS on every ball at BPS.

Who has the MOST consistent gun at what BPS????????? :cheers:

[ThePixelGuru]

Oh ya on a side note and not to be rude but who cares about paint or no paint and air cunsumption? I know I dont.
I was actually quite curious about this. I heard people say that 'mags were less efficient without paint, but they could never prove it to me. Now we not only know it's true of 'mags but most other markers as well.

[GoatBoy]

Was the original thread there removed?? You can post and refer to Tech PB here. Just dont POST ANY LINKS to his or your vids with SWEARING. That guy has a bad potty mouth that is not AOs style.

edit.... Oh ya on a side note and not to be rude but who cares about paint or no paint and air cunsumption? I know I dont.

What I REALLY CARE about is consistency. Get the FPS on every ball at what ever ROF.

At one BPS I have a gun I can get 299, 299, 299, FPS on CO2. Now what will it be at five, ten or fifteen BPS????? Who can chrono EVERY ball at ten or fifteen BPS? Thats FPS on every ball at BPS.

Who has the MOST consistent gun at what BPS????????? :cheers:

We care about the truth.

So when someone claims an efficiency number by dry firing a marker, we will know how to treat their data.

[jackwood]

ill post my theroys after the discussion boils down to something.

one thing i have learned though this all is to keep my damn mouth shut until someone says what i was going to say.

as far as the trigger pull rate, i was as careful as i could be to get a very rythmic pattern going, becuase i also suspected the mechanical timming issues with the cocker would lead to diffrences. we did our best to keep the trigger speeds identical, with all the guns.

Haha, not going to get caught out by the same thing twice, huh? Now yer learnin', as we say "Up North" here in England......

I know you think you pulled the trigger consistently, but in the systems we are talking about here fractions of milliseconds can make considerable differences. Why do you think the Ego has the Dwell resolution set at 0.1ms? Because we liked it? No, because that is the kind of resolution you need if you want accurately control the valve dwell.
If you were to use an electro cocker then you would have the ability (at least with ours) to set the trigger rate electronically to see how it may alter things in this test. Then like ai said, you would need to try different LPR pressures etc as well. You could go on and on and on with a cocker.

[jackwood]

Gordon, just looked at your last MCB post and I think I see what you were implying with the "surprise" result from the cocker.

You expected the Cocker and 'Borg to produce similar figures because they are both poppit, right?

Nooooo, not going to happen. Completely different in every way. Just because they both have a knock-open valve does not mean they work in anything like the same kind of way.

[drg]

I think the point of dryfiring to try to get efficiency is so you can get a number without shooting paint and the associated expense. Personally I just keep track of the balls I shoot over the course of a tank during a normal day of play, but I guess people tend not to run their tanks dry when they have all-day air.

[luke]

:) lol

You said "uumm" 23 times, in a span of 1 minute 42 seconds of tape. On average that is every 4.435 seconds.

:)

[cockerpunk]

jack, im with you 100% percent.

i know without a timming system you can't possibly pull the trigger in a perfet rythm. even with a timing circut, its easy enough to simply measure the time better and all of a sudden your .1 ms resolution is worthless aswell. hell, at work here we bore holes out to .000001 inch resolution, and before i worked here i though +/- .001 in was a tight tollerence.

what i was saying is that i was not rapid firing, then slow shooting for the other test. clearly, that would have an effect that we could see.

yes, i was surpized by teh cocker, yes, but i think i know what is going on now that we have the test data.

[GoatBoy]

So, anyone else run any of their own testing yet?

The field was quiet this weekend, so I decided to run my own tests.

http://spreadsheets.google.com/pub?key=pq_qLVoBwi8hx5Mocq7tBOw

I used a digital scale to measure results.

The HPA results were a little more exaggerated than yours, particularly at the high end.

The CO2 results, on the other hand, were just bizarre. This is the exact same gun used for the HPA test; just the air source was switched out (and I did rechrono to 300fps; today there wasn't much difference). I ran this test twice and came out with the same results.

The only really unusual thing about my setup is that I removed the valve pin from the AIR, and I'm using the Palmer's Stabilizer to perform regulation. Again, same configuration for all tests.


I'm planning to do the same thing with some blowbacks; I have a Spyder coming in a few weeks. I'm more interested in the "low end" gun performance than "high end".

[Hilltop Customs]

GoatBoy, I'm just curious as to what you are interested in finding out with these tests?

your co2 data is very interesting. Its very much like the ion data, counterintuitive.

Seeing all your data in g's makes me wonder the weight difference between an empty air tank, a full air tank and the weight where the remaining air pressure no longer functions the marker properly.

[GoatBoy]

GoatBoy, I'm just curious as to what you are interested in finding out with these tests?

I've never trusted anybody elses data or general rules of thumb (except for, say, Tom Kaye).

The dry-fire thing was just to see if I could see something similar to what cockerpunk got.

The paint tests were to give me an idea of how my guns really operate. I feel I've been lied to enough by other paintballers, so I want my own data now.

Overall, I want to see if some of my calculations make sense.


Seeing all your data in g's makes me wonder the weight difference between an empty air tank, a full air tank and the weight where the remaining air pressure no longer functions the marker properly.

That can actually be calculated.

I just happen to have air in my nitro duck 45ci tank today, and it had a little over 1000PSI according to the gauge (and by the way, I trust my digital scale way more than my little paintball gauge). I threw that on the scale. Then I emptied the tank out and threw that on the scale.

Approximately 1050PSI @ 45ci = 1246g
Empty tank = 1179g

So 1050PSI at 45ci is about 67g.

If I plug in all the Boyle's law stuff that I used earlier, I get 3215ci of air released, which should weigh about... 68.1g. Actually, the tank didn't empty out; there was still 45ci of air inside of there, which was like 0.95g, subtracting that gets about 67.2g.

So my math appears nearly dead-on; the error involved is probably ... my reading of that stupid gauge, and the extra volume added or taken away by the regulator (since that plugs into the tank technically).

If you want to calculate the weight of the tank when your gun stops functioning, then you just pick a PSI and use the equations. Conservatively, on a mag, I'd use about 500PSI as the point where the marker starts feeling bad.

[Hilltop Customs]

thats why I liked the data in g's :cheers: much more accurate data, and since the data is more accurate, calculations made using the data are much more reliable.

what type of scale did you use for this? a postal scale? I have a small digital scale but its limit is 500 g's.

This could also be used for testing out different barrel efficiencies (and testing/verifying optimal solid bore barrel length) :D

edit: and accessory("upgrade") effects on efficiency

[brycelarson]

What's the accuracy on the scale?

[GoatBoy]

I have a couple of run-of-the-mill digital scales at home; one is a Pelouze and the other is some off brand picked up at Harbor Freight. They both measure in terms of grams, so that's roughly the accuracy. Obviously, a single shot can't be measured, so that's why you do things in sets of, say, 100.

[brycelarson]

I have a couple of run-of-the-mill digital scales at home; one is a Pelouze and the other is some off brand picked up at Harbor Freight. They both measure in terms of grams, so that's roughly the accuracy. Obviously, a single shot can't be measured, so that's why you do things in sets of, say, 100.

sure, but using a measuring device that's +/- %10 is a tough sale when measuring something so preciese.

the other number to be concerned with in your instrumentation is repeatability.

what's the display - just grams - or does it give a decimal value?

[GoatBoy]

sure, but using a measuring device that's +/- %10 is a tough sale when measuring something so preciese.

the other number to be concerned with in your instrumentation is repeatability.

what's the display - just grams - or does it give a decimal value?

It's just grams; no decimal places. Think about it for a bit. If I put 1.1g on there, what might it read? if I put a 1.6g on there, what might it read? Why do you think I did the test in batches of 100?

[Hilltop Customs]

even if the error is +/- 1g(worst case round up from .01, or down from .99) that would mean the max the data could be off would be +/- 2 grams since your using 2 measurments to calculate the average......divide that +/- 2g by 100 and your left with +/-.02 g per shot which is only about 10% or less of the value for calculated for g/shot.

as for repeatability, check out the value for the 2 dry fire tests using 50 shots....same g value of 10g. the value for 100 shots is 20g, which fits exactly on the linear relationship of .2g/shot. Id say that shows some good repeatability, but this could be verifyed by more tests, or tests with a more accurate readout/device.

If you want to reduce the error even more, add more shots to the test, or repeat the test and average the results. figure out the g value over 1000 shots and you will still be MAX+/-2x(scale error)......so then the final error will be +-2(scale error)/1000 or +/-.002g/shot.

I just want to say both tests are great, only real difference is what they refrence each shot to(psi or grams) and since pv=nrt they are both essentially equal(ex:1/4 the number of molecules/mass will mean 1/4 the pressure). Since the goal of a paintball gun is to fire the same amt of air at the same pressure for each shot, they both should vary linearly with the number of shots.

What it comes down to is what is the +/- of reading the guage vs the +/- of the digital scale readout.....I'd go with the digital, even if the psi guage is the most accurate in the world you still have to rely on someone to interpret the reading.(look at the guage at a skewed angle and you could easily be off more than the error of a bad digital scale)

[GoatBoy]

bryce:

I don't know how the scale works internally, but intuitively, you have two choices: round or truncate. Let's assume truncation. I'm measuring a delta, and I measure something that is 2.9g on one object, and 1.0g on the other object (I believe this is worst case for truncation). The machine truncates the first measurement to 2, and the other is 1. The measured delta is 1g, when in reality it was 1.9g. I'm off by less than 1 gram when I do the difference, because the same scale should skew the measurements the same way. If I was measuring such small quantities, then my percentage error is huge.

Now, I split the "with paint" into two 50 round measurements completely by accident, because I did 50 rounds and forgot to reload, went and measured and started breaking the gun down to prepare for the CO2 version and suddenly realized I forgot to do another 50. I really intended to do 100 straight, and as my note indicates, I probably need to re-do the data, but at least my repeatability was pretty good.

However, let's assume that I had done it correctly (and I probably will re-do it), and I still yielded a difference of 20g for 100 rounds with paint. I'm off by 1g at most (again, see above), so my max error is really about 5% for that range.

In any event, you're sweating the details, and missing the big picture on repeatability. Let me reiterate.

Your test implementation is not easily repeatable... by other people. Your procedure starts like this:

Step 1: Buy a 13ci tank.
Step 2: Buy an obnoxiously large, unwieldy, and possibly expensive HPA gauge.
Step 3: Install the gauge on the high pressure side of the 13ci tank.

Those three steps right there are already a barrier.

The alternative procedure starts out like this:

Step 1: Get a tank. Any tank. Can be CO2 or HPA.
Step 2: Get a scale that can accommodate your gun+tank's weight.
Step 3: Err, there is no step three, because you don't have to install the scale on the tank.

And then in either case:

Step 4: Fire enough shots to make the average instrumentation error go down

Anyways, I've run the math, and it seems to justify my methods. My experimental result with the emptying of the tank was within 1g of calculated weight with a 67g delta. Perhaps my scale, my gauge, and my math were all wrong in exactly the correct way to be within the same estimated error? If I'm wrong, then perhaps someone would like to... rerun my test and validate my results? You see where this is headed?



Don't get me wrong, I have no problem with your results. I trust you guys are trying your best to be diligent. I'm not trying to contradict your data, because I know there are way, way too many variables involved. It's the design of the test in the grand scheme of things that could use some work.