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M1A "Unitized gas cylinder"

Discussion in 'Rifle Country' started by macman37, Apr 4, 2004.

  1. macman37

    macman37 Well-Known Member

    Is this something someone offers? Or can someone do it themselves?

    And does it void the warranty? Does Springfield offer this service (or at least the part)?

  2. macman37

    macman37 Well-Known Member

    ack, just found one on Brownell's site.

  3. 4v50 Gary

    4v50 Gary Moderator Staff Member

    Methinks that the Springfield match guns have them. BTW, there's two different methods of unitizing them. I was taught the drill & tap method (& stake) which doesn't reveal any exterior modification (necessary for some competitions). Another method is to weld the unit together (but makes it illegal as it is an exterior modification).
  4. longtom4570

    longtom4570 Well-Known Member

    Please to explain what is a unitized gas cylinder?
  5. pbhome71

    pbhome71 Well-Known Member

    I found the following info rom Brownells's site:

    How much accuracy does this improve? It sounds like it helps with POI change dues to sling usage during a match. Is this true?
  6. shoobe01

    shoobe01 Well-Known Member

    How does this work? I mean, literally. How does the gas get from the barrel to this gas system without there being some connection? Lasers?

    If it does work, this is the coolest thing ever. All gas ops should have this designed in at the factory.
  7. Sven

    Sven Senior Member

    Gas leaves the barrel through a tiny hole in one of the lands. As the piston begins moving rearward, the hole is shut off, limiting the amount of gas that can enter.

    Unitizing the system is one of the steps towards accurizing your M1A. For more info, pick up Scott Duff's fine book on the M1A for starters: http://www.scott-duff.com
  8. Steve Smith

    Steve Smith Moderator Emeritus

    Unitized gas cylinders are incredibly common on match and sniper use M14/M1As. If they did not work, they would not be de rigeur for those activities.

    Macman, there are a lot of guys out there that can build you a good M1A. Try Clint Fowler or Smith Enterprises.
  9. shoobe01

    shoobe01 Well-Known Member

    I'm not saying they don't work, I just still don't get /how/. I've been taught that you can't touch anything to the barrel. And there doesn't seem to be any way to get high pressure gas between two non-touching items.

    If anyone knows /exactly/ how and why this works, is there any good reason its not possible to put it on any-old rifle (I don't mean this actual part, I mean the design concept)? Is it picky about being clean or is there something unique to the M14 I am not aware of or what?
  10. Andrew Wyatt

    Andrew Wyatt Well-Known Member

    the entire gas system free floats.
  11. 30Cal

    30Cal Well-Known Member

    The gas system hangs off the barrel. It sits on some splines. The barrel band sits on the barrel and rests between a shoulder milled on the barrel and the gas cylinder. In the picture above, the barrel band is the thin vertical stamped metal part on the right. The front end of the handguard tucks into it. On a stock rifle, the barrel band does a lot of moving around. On a match rifle, the barrel band is screwed or welded to the gas cylinder to eliminate this movement, and then the entire gas system is driven onto the barrel with a mallet. On a stock rifle, the gas system is often loose on the splines. Loose = fliers and shifting zero's.

    The rifle is usually bedded so that the forend of the stock is pulling down on the barrel band w/ 5-40lbs of force. This in tern applies a downward force on the barrel. This will help dampen out all the unwanted vibes that you get after you hang a bunch of gear off the barrel. M14's are seldom freefloated and are usually pretty tempermental if they are.

  12. Sven

    Sven Senior Member

    Here is a picture of a gas assembly from my M1A Gallery:


    On the right you can see the gas piston sticking out.

    As previously outlined, gas enters the top through a hole that goes into the piston when at rest. Gas pushes the piston and thus the op rod - ultimately saving us the task of cycling the action by hand.

    The cylinder fills up with carbon that needs to be cleaned out about every 400-500 rounds to keep the interior volume the same. Groups / POI can suffer elsewise.

    I'm due my first cleaning right now, and will post pictures to show the affects of Lake City M118LR - got my drill bits from a former AMU shooter, great guy.
  13. 4v50 Gary

    4v50 Gary Moderator Staff Member

    How does the unitizing affect accuracy? Why, it reduces the # of moving parts, that's how. The fewer moving parts, the more consistent the harmonics of the gun. Think of the rifle receiver & barrel as a tuning fork. Anything attached to that tuning fork causes it to vibrate at certain frequencies. If the attachment is moved up or down the fork, then the frequency at which it vibrates will vary and thus Watson, the groups will vary too.

    Per se the M-14 barrel isn't really free floated as you've got that Unitized Gas Cylinder hanging off of it and it's in contact (preferably bedded) to the stock (where the unitized ferrule meets the stock).

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