Page 1 of 2 12 LastLast
Results 1 to 30 of 50

Thread: Barrel Efficiency, Tech Tip #1

  1. #1
    Join Date
    Oct 2000
    Location
    Chicago
    Posts
    5,953

    Post Barrel Efficiency, Tech Tip #1


    Guys,

    I have decided to do a tech tips series of posts so you will understand certain technical processes that go on in the paintball gun. We have tested everything I will talk about and any speculations will be pointed out.

    In the tech forum there is a long post on what is the most efficient barrel so here are the facts.

    Barrel Efficiency, Tech Tip #1

    Barrels are only there to accelerate the ball from a standstill to 300 fps. In theory they also help with accuracy but that's another post. The ball goes through incredible acceleration on its way down the barrel. The balls acceleration rate is approx. 50,000 feet per second to get to 300 feet per second in 10 inches. The entire barrel travel time is about 6 thousandths of a second and this means the ball is seeing about 1500 G's when its getting pushed out the gun. Although this may sound incredible if someone out there would like to do the math you will see that I'm close.

    Air pressure behind the ball is what causes this acceleration to happen. This pressure varies between the different guns but is generally between 50 to 125 pounds per square inch at its peak. The air pressure peaks right when the ball starts moving down the barrel, after that, the ball moving down the barrel creates a bigger chamber so the pressure drops. This is why low pressure guns are a myth, in reality all guns shoot at considerably lower pressure than 200 psi.

    Peak pressures above 150 psi tends to break balls down the barrel due to really high acceleration and G forces. If you don't have any way to control the peak pressure behind the ball, the only way you can change it is to go with lower pressure in the air chamber, hence low pressure guns. AGD uses the precise contour of the power tube tip to release air in a controlled manner behind the ball to limit peak pressures to around 60-80 psi..

    It is simple to understand that the harder you push something the faster it will accelerate and get up to speed in a shorter distance. So what distance do we have to get the ball up to speed? The effective length of the barrel is from the balls position before it's fired, to the place in the barrel where the pressure gets released, This is usually at the first porting holes or the step in the barrel. Porting is there to release gas pressure!! You are effectively stopping the acceleration at the ports so your 14" barrel that is half full of holes only has an effective length of 7".

    Now we understand that we need to limit the peak pressure behind the ball to keep it from blowing up, and that the pressure drops as the ball moves down the barrel. The next question we need to ask is, how far down the barrel does the ball have to go before the pressure gets to low to do anything useful? That answer is 8-10 inches. We know this from looking at the graphs that our gun dyno puts out. If your peak pressure is higher, say over 100 psi you can get away with a shorter barrel, if it's lower then you need a longer barrel. Since AGD is the only gun manufacturer to actually test their pressures behind the ball you might have a hard time getting this info for other guns.

    So as far as our guns are concerned, the best efficiency would be had with an 8-10" effective length barrel. Since two piece ported barrels with an effective length of about 5-6" are the rage right now you hear a lot of complaints about gas efficiency. Under some circumstances there is a good reason to use a short effective length barrel. Short barrels cut off the acceleration abruptly by venting and this has the effect of tightening up the shot to shot velocity variation. If you need this at the expense of efficiency then go ahead. Tighter velocity control usually translates into some improvement in accuracy due to better consistency.

    So if you want the best of all worlds, limit your peak pressure, let your ball accelerate all it wants, don't follow the crowd and keep asking questions.

    AGD

  2. #2
    Join Date
    Oct 2000
    Location
    Las Vegas, NV
    Posts
    7,104

    Post

    Hey now! This is a great idea... hope you have a permanent place to put this so we can all go "See, I told ya so, says right here."

    ------------------
    'Sacrifice the Body'
    68 PF - HyperFrame - 68 Flatline - SS BigShot

    Miscue's Profile

  3. #3
    Join Date
    Jun 2001
    Location
    East Lansing Mi, US
    Posts
    256

    Post

    Gee, I've been telling people that before... Not with the exact numbers, though. Plus I am no rocket scientist. 12in Lapco Bigshot-"effective" length of around 10 inches. I don't have mine here to measure, but the only porting on the thing is in a band right before the muzzle break.

    ------------------
    "Don't spend so much on parts that you can't afford to play."

  4. #4
    Join Date
    Mar 2001
    Location
    Miami, FL, United States of America
    Posts
    1,807

    Post

    For those of you who don't understand a Barrel that has more effective barrel length is more gas effecient. Effective barrel length is the portion of the barrel that is unported. However barrels with less effective barrel length and more porting give you tighter shot grouping(more accuaracy). I know Tom explained it well but I didn't understand at first I thought I might as well simplify it further.


  5. #5
    Join Date
    Jan 2001
    Location
    WWW.INCEPTIONDESIGNS.COM
    Posts
    3,817

    Post

    <font face="Verdana, Helvetica, sans-serif" size="2">Originally posted by AGD:
    Barrels are only there to accelerate the ball from a standstill to 300 fps. In theory they also help with accuracy but that's another post.</font>
    I'd like to read that other post please when you get time

    thanks

    manike


  6. #6
    Join Date
    Feb 2001
    Location
    Where the beer is deep. The forest is funny colored. Cloud nine is a thought away.
    Posts
    2,321

    Post

    Finally Im going to make use of my printer

  7. #7
    Join Date
    Feb 2001
    Location
    Where the beer is deep. The forest is funny colored. Cloud nine is a thought away.
    Posts
    2,321

    Post

    oh yeah and that means the 98 only has like 4 inches of barrel.... damn

  8. #8
    Join Date
    Jan 2001
    Location
    Cottonwood, Az.
    Posts
    5,780

    Post

    Cool, meat and potatoes, I like it!

  9. #9
    Join Date
    Dec 1969
    Location
    "The SC" (South Carolina)
    Posts
    16,205

    Post

    Sorry to hear you are in "rain delay" but you loss is our gain. You got time on your hands huh?

    Phil

  10. #10
    Join Date
    May 2001
    Location
    Richmond VA
    Posts
    1,097

    Thumbs up

    Good information. Stuff I've known about (except for the AGD testing info) but still a good refresher.


    DR

    ------------------
    Owned a PF mag in 96.
    =)

  11. #11
    Join Date
    Nov 2000
    Location
    dalton,ga, usa
    Posts
    593

    Cool

    isn't it nice to know and talk to someone who knows what they are talking about. Later AZZKIKR

  12. #12

    Question

    What about bore sizing? Is it as substantial an issue as it's been made to be lately, or is it not so important (ref. the Palmer theory of the paintball distorting under the initial impact of the airburst so that all sides are in contact with the barrel breech when acceleration begins)?

  13. #13
    Join Date
    Jan 2001
    Location
    Cottonwood, Az.
    Posts
    5,780

    Post


    Jeb_Hoge,

    EXCELLENT question! AGD..............

  14. #14
    Join Date
    Jun 2001
    Location
    some field in NoVA with a ton of pods ready to be dumped
    Posts
    2,950

    Post

    how does a stock Emag/RT barrel's efficancy compare to a 12" DYE one peice barrel..?

  15. #15

    Post

    So the effective barrel lenth is before the porting starts on an unsteped barrel.

  16. #16
    Join Date
    May 2001
    Location
    Houston, Tx
    Posts
    477

    Post

    whoa... i actually learned something... Gun Dyno's!

  17. #17
    chaoticorigin Guest

    Post

    The Dye 12" one piece has 7" of unported length. Shouldn't I measure the length from the beginning of the paintball? It would be less then. I was thinking of putting tape around the gun end of the porting covering about an inch so wouldn't that in effect make the barrel more efficient?

    The 2 piece dynamics confuses me a little. As the paintball goes to the 2nd step. Doesn't the ball continue to accelerate until it hits the porting? I think the acceleration should still continue but at a lower acceleration because the bore is larger. I gotta try some experiments this weekend with a boomstick. I heard 8-12 was the ideal unported barrel length.

    Why doesn't AGD make some good barrels as an optional buy? They seem the most serious about paintball dynamics. My stock barrel shoots decent but it doesn't have a mirror finish interior which gives less friction.

  18. #18
    Join Date
    May 2001
    Location
    Irvine, CA, USA
    Posts
    13

    Post

    Excellent info. Now this is quality service to your customers

    Keep it coming and many thanks. Maybe sometime you will address the biggest paintball myth... that closed bolt guns shoot farther than open bolt guns.


  19. #19
    Join Date
    Jan 2001
    Location
    Seattle, WA
    Posts
    104

    Post

    This is exactly why I've played with a mag for over ten years. AGD never talks any smack about other manufacturers but if you ask the right question they will give you the answer and back it up with real science and data. From there they let us make a decision based on fact not hype.

    Tom, is www.paintballphysics.com ever going to become a reality or will the info just be put in the tech tips area?

  20. #20
    Join Date
    Jun 2001
    Location
    East Lansing Mi, US
    Posts
    256

    Wink

    Speaking of closed bolt vs. open bolt-

    http://www.warpig.com/paintball/tech...osedopen.shtml

    Who other than WARPIG and AGD should we rely on to confuse us, stun us, educate us, and entertain us?

    ------------------
    "Don't spend so much on parts that you can't afford to play."

  21. #21
    Join Date
    Jun 2001
    Location
    topeka, kansas, usa
    Posts
    31

    Thumbs up

    Thumbs up to AGD for their markers, their advice and the awesome customer servie they provide.

  22. #22
    Join Date
    Jan 2001
    Location
    WWW.INCEPTIONDESIGNS.COM
    Posts
    3,817

    Post

    Now paintballphysics.com is definitely a site I would like to see.

    Open up those archives and show the world some real data although the 2inch folder on mag bumpers could probably be left in the draw...

    I would really like to have that film of the ball being shot through a glass barrel available for all. The close up of the ball in the breech and the ball exiting through the smoke trail (I know there's a bit on the RT video). As well as the ball in flight, that stuff is amazing to watch.

    I also think some barrel testing with and without ports and some sort of trace element in the gas to actually see if it does exit the ports behind the ball as it goes past would be very interesting!

    How about a new breed of two piece glass barrels lol... gotta keep up with fashion

    manike

  23. #23
    Join Date
    Feb 2001
    Location
    Corning NY
    Posts
    22

    Question

    So whats the Dilly? Why do they put porting on barrels then??

  24. #24
    Join Date
    May 2001
    Location
    Raleigh, NC, USA
    Posts
    290

    Post

    manike, along with glass barrels we'd need colored N2 :-)

  25. #25
    Join Date
    Feb 2001
    Location
    Old Town, Maine
    Posts
    1,333

    Post

    WoW, Tom To Much Spare Time...

  26. #26
    Join Date
    Oct 2000
    Location
    Kansas City, MO USA
    Posts
    1,765

    Post

    HEY MANIKE! Nice to see you on here, mate! Sure theres lots of stuff you can contribute!

    take care!

    ------------------
    Webmaster - AutoMags.Org
    webmaster@automags.org
    ----------------------
    "Good...bad...I'm the guy with the gun." - Ash, Army of Darkness

  27. #27
    Join Date
    Jun 2001
    Location
    Rio Piedras, Puerto Rico, United States
    Posts
    23

    Post

    Great info!! That's why AGD makes the best guns in the business.

  28. #28

    Post

    Firewall,
    Porting is there to release gas pressure and to quiet the sound. An unported barrel is very loud when you fire a paintball through it.
    So it's like a tradeoff:
    Unported = loud but more gas efficient
    Ported = quieter but less gas efficient

    Gotta find that happy medium ssomewhere...

    ------------------
    Black Teflon ReTro Mag
    Warped Sportz Drop Forward
    68ci/4500psi Centerflag Hyperflow 420 tank
    Benchmark 45 grip frame w/Dye sticky grips
    KAPP foregrip extender w/Benchmark foregrip

  29. #29
    Join Date
    Jan 2001
    Location
    WWW.INCEPTIONDESIGNS.COM
    Posts
    3,817

    Post

    <font face="Verdana, Helvetica, sans-serif" size="2">Originally posted by Webmaster:
    HEY MANIKE! Nice to see you on here, mate! Sure theres lots of stuff you can contribute!

    take care!
    </font>
    OK I'm wondering who the webmaster is... My Yanky friend John? How's the theory of light speed travel going? And the Religious debating?

    or another of the crew Eric?

    It's not one of the brit John's is it? Hiding behind a Kansas City Origin, lol.

    I have a suspicion it's Bonich, but the US origin bit is throwing me... If it is JonBon we need to talk some CAD/CAM stuff matey

    Ahh just had a thought... it's not Mr44 is it?

    Bill posts under something else so it aint him, Dawn? .... aarrrgghh too many possibilities

    manike

    [This message has been edited by manike (edited 06-19-2001).]

  30. #30
    Join Date
    Jun 2001
    Location
    Esparto, CA
    Posts
    552

    Exclamation

    Man, I hate to do this: I believe you have the acceleration rates wrong. They are a bit overstated. The rate to push the ball is not 50,000 fps. That is about the escape velocity to achieve earth orbit. To hit that number in 10 inches would push the g-forces to over 22,000, enough to permanetly compress titanium. If you are talking about the initial acceleration from zero to any number, that is proportionally the highest attainable acceleration number on the curve, and mathmatically approaches infinity. Also, if you did go to 50,000 fps, you have to decelerate the ball down to the 300 fps mark and therefore put the paintball through double the stress. Am I off-base here, or did I miss something? Brent Jackson, Pink Fluffy Ballerinas.

Similar Threads

  1. Effective barrel length
    By rakshasagenn in forum Automags - Tech Forum
    Replies: 8
    Last Post: 12-18-2002, 05:22 PM
  2. Freak Tip Sizes and Types (by request)
    By cphilip in forum Paintball Talk
    Replies: 3
    Last Post: 08-28-2001, 01:19 AM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •