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gas ram /spring power comparison

Discussion in 'Anything Airgun Related' started by peterpan, Jan 9, 2014.

  1. peterpan

    peterpan Engaging Member

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    Been doing a lot of reading up on gas ram air rifle as I now own one.and iv read that a gas ram or pcp air rifle putting out the same power as a spring rifle will produce more power and have better power down range. Would be interested to know how this can be as the pellet leaves the barrel at the same speed even if it is a spring rifle
     
  2. 177

    177 Donator

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    Never heard that one before.

    Sounds like "a ton of lead vs a ton of feathers" or possibly one of the great unwashed internet 'facts'.

    If a gas ram, spring gun and PCP all shove a 16 gr pellet downrange at 580 FPS they're all pushing the same 11.95 foot pounds energy. Assuming all three guns shoot exactly the same FPS their power will also be identical, and downrange the same ought to be true assuming they are all using the same pellet, which will drop at the same rate...

    If one somehow contrives to deliver more power than the others 30 yards downrange I'd be interested to find out how as well :)
     
  3. cloverleaf

    cloverleaf Super Moderator Staff Member Mod/Admin

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    The short and simple answer to the supposition that "a gas ram or pcp air rifle putting out the same power [energy] as a spring rifle [at the muzzle?] will.. have better power [more energy] down range", is that it's it's not true.

    By and large your assumption is correct that the same pellet fired at the same velocity into the same environment will shed energy at the same rate, regardless of the type of rifle it was fired from.

    The longer and more correct answer is that the drag characteristics of the pellet are influenced both by the way the air is delivered to the rear of the pellet (namely the peak pressure attained and how it "blows out" the pellet's skirt) and the extent to which it's circumference is deformed by the rifling; so it's possible that the energy retained down range by two identical pellets fired at the same velocity from different guns/barrels will vary slightly; but certainly not to a significant extent ;)
     
  4. Meteor62

    Meteor62 Major Poster

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    Same power is same power
     
  5. Wild Bill

    Wild Bill Long time poster

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    Unless you shoot downhill on a Sunday. :)
     
  6. Tinbum

    Tinbum Delusions of adequacy

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    Or if you're using a smooth twist barrel! The lack of rifling marks improves the BC and will improve downrange performance.





    (A bit)
     
  7. JD

    JD Donator

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    The only thing that seperates a gam ram from a springer is the lock time.
     
  8. Wild Bill

    Wild Bill Long time poster

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    And the lack of a spring in one of them. ;)
     
  9. smithys

    smithys Busy Member

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    But quieter smother less vibration an done correctly there better, but you either love them or hate them,
    Also correct lube an ptfe piston seal combine with breach upgrade and a litle polish, then they can be even better, also lighter piston can Improve the ram if your looking for pure smooth over power, I made my own floating weight to reduce recoil, not to far off whats in my sirocco,
     
  10. Accuspell

    Accuspell Pro Poster

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    You have all overlooked the perpetual motion aspect of the gas ram. The gas ram conforms to Susan Boyle's law.:up:
     
  11. 1961nuffield

    1961nuffield Honorary Member

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    Almost impossible to understand the popularity of, but seems quite successful despite that :D

    John
     
  12. peterpan

    peterpan Engaging Member

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    Thanks for all your replys i read the artical from pyramid air guns about benifits of gas rams .iv got one in my 177carbine supersport and it sits quite nice at just under 10 ftp which seems to be plenty. Its a very good tool
     
  13. Fred_Bear

    Fred_Bear Well-Known Member

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    So does that mean any rough looking gun conforms to the Susan Boyle law?

    Good page here:
    http://uncyclopedia.wikia.com/wiki/Susan_Boyle
     
  14. whitevanman574

    whitevanman574 bell target champion

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    ive got a webley tracker with a gas ram in it certainly shoots better than one with a spring ever did to ....
     
  15. Darren Petts

    Darren Petts Temporarily Alive

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    There is a difference between a pcp and a springer in that the springer will blow the skirt of a pellet out more harshly into the rifling. This in turn creates a more aerodynamic shape with a better BC and the result is quite measurable downrange. There is a difference between a ram and a springer in a similar manner but to a much lesser extent than that between a pcp and springer.
     
  16. 177

    177 Donator

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    so is this significant enough to give a tangible benefit between three guns (gas ram, spring and PCP) that all spit the same pellet out at the same FPS ?

    Tangible, as in, your average shooter would be able to see it without some sort of scientific jiggery pokery ?

    The reason I ask is that any measurable difference would surely be more difficult to capitalise on using a gun that, by definition, is more difficult to shoot well to begin with.

    Just thinking out loud based on curiosity...
     
  17. Darren Petts

    Darren Petts Temporarily Alive

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    For 99.9% of shooters the ease of extracting the accuracy out of a pcp will easily outweigh the benefits that the recoilers have in BC. All other factors being equal you will need to alter your holdovers to compensate for the difference though. From memory the differences I got were around 1/3 of an inch less drop over 55 yds in .177 from the boingers.
     
  18. Accuspell

    Accuspell Pro Poster

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    You can SEE to 1/3 of an inch at 55 yards? :eek: I am lucky if I can see an entire pigeon at that range! :D
     
  19. Dunkman

    Dunkman Posting Addict

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    That theory has to be highly speculative. Regardless of whether or not there is any difference between a PCP or a springers ability to blow the pellet skirt into the rifling, the variables that immediately come to my mind are the difference in the design and thickness of skirts on pellets (this probably makes more difference to the engagement with rifling than whether a PCP or springer is providing the puff) and the difference in barrel specs between guns (Choked or not) and then the actual difference in pellet sizes from different pellet manufaturers also affecting how the skirt is formed by the rifling. This is evidenced by how some barrels prefer some pellets over others.
     
  20. Darren Petts

    Darren Petts Temporarily Alive

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    I don't regard most of that as theory or speculation at all. I believe others have reached similar conclusions too from their own observations. From firing into a soft medium the springer or ram does indeed blow the skirt much harder than a pcp does. A spring gun requires only a small (7-8") barrel to hit 12 ft/lb velocities but a pcp typically uses a 14-18" barrel. Ergo the spring gun is accelerating the pellet much harder. From the reduced drop of the pellet noted across several spring guns compared to several pcps there is a BC difference consistently in favour of the springer. Given the pellets started out the same in terms of shape and speed the change in shape is the only realistic explanation for the increased BC. If it was one springer versus one pcp I'd grant the term "theory" as any two guns can give different BC values to the same pellet but I've noted it across enough guns to be convinced. There is a caveat in that all my observations were done in .177 with their relatively soft skirts. .22 pellets have much stronger skirts and my well not exhibit the same degree of deformation differences.
    I will readily accept that I haven't seen enough data to be certain the ram has a similar but much lesser advantage over the springer. The little data I have seen is others work and could be variations from one to another gun rather than generic from one power source to the other. The little data I've seen did give the nod to the ram though. More data needed.
     

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