Page 5 of 10 FirstFirst ... 34567 ... LastLast
Results 41 to 50 of 100

Thread: DI or Piston?

  1. #41
    Join Date
    Jun 2007
    Location
    The Free State of Nebraska
    Posts
    4,786
    Feedback Score
    6 (100%)
    Quote Originally Posted by Spartan040 View Post
    Looking to build an AR for myself, can't decide if I want direct impingement or piston. Piston runs cleaner and cooler and (I've heard) can generally take more abuse and less lube before it begins to fail, and if there are minimal reductions in accuracy and a tiny bit more felt recoil, I don't really mind. But, I've heard there are certain mechanical issues associated with piston AR's. I wanted to know what they are, and if there's anything that can be done to fix them in a custom build. I've also heard availability and interchangeability of parts is another factor. Are the advantages of the GP system worth the trade-offs?

    You will not be building a piston AR-15.

    Every "bolt on" piston kit is garbage.

    If you want a piston, then you must by from Colt, HK, LWRC, or LMT.
    "Not every thing on Earth requires an aftermarket upgrade." demigod/markm

  2. #42
    Join Date
    Jun 2007
    Location
    The Free State of Nebraska
    Posts
    4,786
    Feedback Score
    6 (100%)
    One of the problems with the LWRC systems is you must remove the top handguard to service the piston linkage. Any laser or sighting devices installed on the top rail has to be re-zeroed again.

    The Colt and LMT systems pull out the front of the gas block and don't require any handguard removal. Plus they use a true monolith system.

    On the HK system, the entire handguard must be removed to service the piston linkage, which again I don't like.
    Last edited by scottryan; 04-21-17 at 12:16.
    "Not every thing on Earth requires an aftermarket upgrade." demigod/markm

  3. #43
    Join Date
    Sep 2014
    Posts
    46
    Feedback Score
    0
    Quote Originally Posted by scottryan View Post
    Every "bolt on" piston kit is garbage.

    If you want a piston, then you must by from Colt, HK, LWRC, or LMT.
    Agree with the first statement but curious why PWS doesn't make cut? They have the most elegant system by far. And servicing the piston and piston tube is pretty straightforward.

  4. #44
    Join Date
    Nov 2009
    Location
    Norway
    Posts
    1,431
    Feedback Score
    0
    Quote Originally Posted by vicious_cb View Post
    This is why threads like this need to be immediately locked. They all eventually devolve into discussion of minutiae of shit that doesnt really matter to an end user.

    ALL GUNS WILL LOCKUP WHEN FROZEN. Just dont be stupid enough to take your gun inside and let it sweat then take it out in the snow again.

    Instead of worrying about piston vs DI in the snow, worry about how to bivvy and dry off before you freeze to death. Or how to catch a hot MG3 barrel during a barrel change cause you aint getting it back if you miss...
    Yup.

    And you will get the MG3 barrel back - in the spring!
    It's not about surviving, it's about winning!

  5. #45
    Join Date
    Nov 2009
    Location
    Norway
    Posts
    1,431
    Feedback Score
    0
    Quote Originally Posted by MistWolf View Post
    As a whole, a FAL is a different animal, but the gas block and piston are very similar. There aren't many variations to choose from. The physics don't change. The laws of thermodynamics don't change. The laws of fluid dynamics don't change. It's not voodoo. It's science and not that difficult to understand. There is nothing magical about any of the gas systems
    Have you shot an FN Minimi? Or FN MAG? I can tell you that there is a huge difference in fouling and how the cycle of operation works between those and a short stroke gas piston AR like the HK416.
    It's not about surviving, it's about winning!

  6. #46
    Join Date
    Dec 2009
    Location
    Utah
    Posts
    6,670
    Feedback Score
    3 (100%)
    Quote Originally Posted by Arctic1 View Post
    Have you shot an FN Minimi? Or FN MAG? I can tell you that there is a huge difference in fouling and how the cycle of operation works between those and a short stroke gas piston AR like the HK416.
    Each family of weapons is a unique compound machine. But they are made up from the same basic six simple machines. They all follow the same laws of physics. Once that is understood, it's easy to see the similarities. It becomes easy to understand, for example, that the gas holds more heat at the gas block and how it cools as it travels through a tube. It becomes obvious that the face of a small diameter piston exposed to gas with more heat is going to get hotter than the face a larger diameter piston exposed to gas holding less heat.

    That does not translate into "A" is bad and "B" is good, it is a simple statement of fact. People started repeating the marketing hype of how a "piston" system is cleaner and cooler than a "DI" (sic) system without looking at the science. Just like they started repeating how a "piston" system is heavier and has more recoil, again without looking at the science. Baloney!

    The ammo is going to generate the same amount of energy in the form of heat and recoil and the same amount of fouling no matter what gas system the weapon it's fired in uses. If there is extra recoil because the reciprocating mass is moving too fast and bottoming out too hard, the weapon is over gassed.

    A "piston" AR might be two, three or maybe four ounces heavier because the op rod might be that much heavier than the gas tube it replaces. Most "piston" uppers that are heavier have heavier profile barrels.

    Because of your challenges, I have taken a closer look at the science because I know the science is right. Examining the science closer has helped me understand it better. Pistons still get heated and coated with fouling whether they're part of a long stroke or short stroke system, or if the piston is in the carrier or the gas block. Lube helps keep fouling moist and soft. Heat causes fouling to dry and harden. Do any of the systems you're talking about change these facts? Don't be dismissive. Show me the science
    Quote Originally Posted by markm View Post
    Nothing sucks more than too much gas
    "I NEED A CLIP!!"

    http://i115.photobucket.com/albums/n289/SgtSongDog/AR%20Carbine/DSC_0114.jpg
    I am American

  7. #47
    Join Date
    Sep 2012
    Location
    Washington State
    Posts
    422
    Feedback Score
    1 (100%)
    I'm seeing a strawman appear here regarding the cleanliness issue, and interestingly enough I'm also seeing some take on advocacy for the strawman after the fact. This seems futile to me - I can't think of any trends in AARs from classes, the field or the range which have either system failing *with* proper lube strictly due to gas related fouling which would be exclusive of the other of the two systems. That is to say, there are just too few circumstances where one would be found saying, "if only I had been running the other system, my weapon wouldn't have failed due to this gas-related fouling." Being clean isn't an issue at all, but it seems like that is exactly where this discussion has fallen.

    Our Stoner rifle was designed from the ground up as is - not as an external piston design. That in itself lends a sort-of home field advantage to the traditional "DI" system in an AR versus a proprietary external piston. What I'd truly like to see is a good discussion worthy of M4C which more technically discusses the pros and cons of the Stoner's "DI" versus traditional piston systems in a nutshell, as if a whole new weapon were being developed here in M4C. I'd enjoy reading and contributing to that, but that's just me.
    Nobody ever got shot climbing over the wall into East Berlin.

    Delivering the most precision possible, at the greatest distance possible, with the highest rate of fire possible.

  8. #48
    Join Date
    Nov 2009
    Location
    Norway
    Posts
    1,431
    Feedback Score
    0
    Quote Originally Posted by MistWolf View Post
    Each family of weapons is a unique compound machine. But they are made up from the same basic six simple machines. They all follow the same laws of physics. Once that is understood, it's easy to see the similarities. It becomes easy to understand, for example, that the gas holds more heat at the gas block and how it cools as it travels through a tube. It becomes obvious that the face of a small diameter piston exposed to gas with more heat is going to get hotter than the face a larger diameter piston exposed to gas holding less heat.

    That does not translate into "A" is bad and "B" is good, it is a simple statement of fact. People started repeating the marketing hype of how a "piston" system is cleaner and cooler than a "DI" (sic) system without looking at the science. Just like they started repeating how a "piston" system is heavier and has more recoil, again without looking at the science. Baloney!

    The ammo is going to generate the same amount of energy in the form of heat and recoil and the same amount of fouling no matter what gas system the weapon it's fired in uses. If there is extra recoil because the reciprocating mass is moving too fast and bottoming out too hard, the weapon is over gassed.

    A "piston" AR might be two, three or maybe four ounces heavier because the op rod might be that much heavier than the gas tube it replaces. Most "piston" uppers that are heavier have heavier profile barrels.

    Because of your challenges, I have taken a closer look at the science because I know the science is right. Examining the science closer has helped me understand it better. Pistons still get heated and coated with fouling whether they're part of a long stroke or short stroke system, or if the piston is in the carrier or the gas block. Lube helps keep fouling moist and soft. Heat causes fouling to dry and harden. Do any of the systems you're talking about change these facts? Don't be dismissive. Show me the science
    I don't need science to see that a short stroke piston AR has less fouling in the upper and lower than a tradition DI gun.
    That is a fact, and if you had had anything but theoretical knowledge on the subject matter, you would also have seen this. Get one and shoot 1000 rounds side by side, and show me the difference. If you deny this, you clearly show that you don't know what you are talking about

    There is less heating of the bolt, bolt carrier and associated parts on a short stroke piston gun than there is on a DI gun. That is fact, and has been measured using heat imaging. I'll try to dig up the images later today.

    Barrel, chamber and gas block temps run about the same, depending on barrel profile. I'll try to dig up the images later today.
    Last edited by Arctic1; 04-21-17 at 14:44.
    It's not about surviving, it's about winning!

  9. #49
    Join Date
    Sep 2012
    Location
    Washington State
    Posts
    422
    Feedback Score
    1 (100%)
    Quote Originally Posted by Arctic1 View Post
    I don't need science to see that a short stroke piston AR has less fouling in the uper and lower than a tradition DI gun.
    That is a fact, and if you had had anything but theoretical knowledge on the subject matter, you would also have seen this. Get one and shoot 1000 rounds side by side, and show me the difference. If you deny this, you clearly show that you don't know what you are talking about

    There is less heating of the bolt, bolt carrier and associated parts on a short stroke piston gun than there is on a DI gun. That is fact, and has been measured using heat imaging. I'll try to dig up the images later today.

    Barrel, chamber and gas block temps run about the same, depending on barrel profile. I'll try to dig up the images later today.
    You're correct in the observations, and you will be rebutted with the statement that those observations have no practical consequences, which is also correct. The bolt is hotter - so what? Carbon in the upper - so what?
    Nobody ever got shot climbing over the wall into East Berlin.

    Delivering the most precision possible, at the greatest distance possible, with the highest rate of fire possible.

  10. #50
    Join Date
    Sep 2007
    Posts
    1,404
    Feedback Score
    17 (100%)


Page 5 of 10 FirstFirst ... 34567 ... LastLast

Bookmarks

Posting Permissions

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