AR-15 Dissipator vs. M4gery

AR-15 Dissipator vs. M4gery

This is a discussion on AR-15 Dissipator vs. M4gery within the Defensive Rifles & Shotgun Discussion forums, part of the Related Topics category; I'm looking at taking the plunge into the AR world and getting a CQB-type rifle. I like the looks of the M4gery, but have been ...

Results 1 to 11 of 11

Thread: AR-15 Dissipator vs. M4gery

  1. #1
    Senior Member Array Herknav's Avatar
    Join Date
    Mar 2007
    Location
    Waypoint 0
    Posts
    986

    AR-15 Dissipator vs. M4gery

    I'm looking at taking the plunge into the AR world and getting a CQB-type rifle. I like the looks of the M4gery, but have been told the Dissipator might be a better choice b/c of gas tube placement. Any thoughts?
    I would rather wake up in the middle of nowhere than in any city on Earth.--Steve McQueen


  2. #2
    Administrator
    Array SIXTO's Avatar
    Join Date
    Oct 2006
    Location
    Ohio
    Posts
    20,322
    The dissapator is a better choice in most circumstances, not only for the gas tube, but because you get a longer sight radius with the same overall length. I think they are not very popular because the look different than what we are used to seeing on TV etc.
    "Just blame Sixto"

  3. #3
    VIP Member Array Rob72's Avatar
    Join Date
    May 2005
    Location
    OK
    Posts
    3,468
    Most folks don't need (or benefit from)the M4 profile. If your desire is a lightweight carbine, go fluted- it has more length-rigidity than the M4 style. The Dissipator is heavier, and has the other advantages noted by Sixto.

  4. #4
    Lead Moderator
    Array rocky's Avatar
    Join Date
    Jan 2005
    Location
    MI
    Posts
    16,219
    The dissy models do benefit from a longer sight radius. Also a longer gas tube may be more dependable in cycling reliably. Most M4 gas tubes work just fine too (as witnessed from all the M4 clones on the market).
    Down sides of a Dissy would be harder to find parts= i.e. -gas tube-hand guards(not all that hard) but the M4 are much more popular.
    "In matters of style, swim with the current; in matters of principle, stand like a rock." Thomas Jefferson


    Nemo Me Impune Lacesset

  5. #5
    BAC
    BAC is offline
    VIP Member Array BAC's Avatar
    Join Date
    May 2007
    Location
    Tampa, FL
    Posts
    2,292
    Quote Originally Posted by Herknav View Post
    I'm looking at taking the plunge into the AR world and getting a CQB-type rifle. I like the looks of the M4gery, but have been told the Dissipator might be a better choice b/c of gas tube placement. Any thoughts?
    Could you describe what you mean by "Dissipator"?

    If you're talking about the Bushmaster variety, the only difference between it and an M4 look-alike is the longer sight radius. Both use a carbine-length gas system, but the Dissipator will have a low-profile gas port and a front sight base that servers only as a sighting tool instead of as a sighting tool + gas block.

    On the other hand, if you're talking about a "Dissipator" look-alike, meaning, a carbine with a rifle-length gas port, that's a whole different animal. Here's a brief summary I wrote on another site I frequent:

    ...the length of the gas system isn’t necessarily what makes the rifle reliable, rather the length of the gas system in relation to the length of the barrel. This determines dwell time. The best way it’s been defined to me is as follows: “The amount of time between the gas pressurizing the gas system and the pressure equalizing with the outside [of the muzzle] is the dwell time. If that time is too short then the pressure will drop before the bolt has been pushed open and the weapon will not cycle correctly.” That being said, a rifle and a carbine have almost identical dwell times.

    The first carbines had issues with overgassing their actions because the gas port was too early on the barrel (too much dwell time). The fear of the 16” barrel and rifle-length gas system is that the pressure would leave the barrel and equalize before it has had a chance to fully cycle the action (too little dwell time). To my knowledge the best way to handle this has been to drill out the gas port (to .095 and bigger) so more gas can enter the port and cycle the action, and this solution appears to have worked reliably. Both the carbine and rifle length systems are about as reliable. However, the carbine-length system is more “violent” on the rest of the rifle, and will wear its parts down quicker than the longer rifle-length gas system will.
    This principle still applies to standard 14.5" barrels. A carbine is fine and plenty reliable, but a mid-length, rifle, or mid-length/rifle gas system on a shorter barrel will all be smoother (folks who are recoil-sensitive, like kids, wives, first time shooters, etc. will be better off than with the carbine) while shooting.

    If you choose the longer gas system on the shorter barrel, be prepared to have a rifle generally picky with ammo (it'll favor the hotter loads) and that might need playing with the gas port size.


    -B

  6. #6
    Senior Member Array Shizzlemah's Avatar
    Join Date
    May 2006
    Location
    Maine
    Posts
    723
    an AR will not run with the gas port really close to the muzzle. they need to be a couple of inches back. a dissipator has a front sight for aiming, but the gas port is a few inches back - using a standard carbine gas tube.

  7. #7
    Member Array roadsiderob's Avatar
    Join Date
    Oct 2007
    Location
    Albuquerque, NM
    Posts
    199
    I have an 18" barrel with a rifle length gas system on one of my ARs. It will not cycle reliably with low power ammo. Wolf and UMC give it fits. I haven't played with the gas port yet, but all things being equal, I wouldn't build another one. The carbine with the midlength gas system is a smooth running machine. Definitely my favorite.

  8. #8
    Senior Member Array Herknav's Avatar
    Join Date
    Mar 2007
    Location
    Waypoint 0
    Posts
    986
    BAC--I was talking about the Bushy variety.

    Gents, thanks for the responses so far!

    Herk
    I would rather wake up in the middle of nowhere than in any city on Earth.--Steve McQueen

  9. #9
    Administrator
    Array SIXTO's Avatar
    Join Date
    Oct 2006
    Location
    Ohio
    Posts
    20,322
    As BAC pointed out, the Bushmaster isnt a true dissipator, but it does provide a better sight radius and perhaps some more options if you like a bunch of junk hanging off your rifle. And it just different from the ordinary.
    "Just blame Sixto"

  10. #10
    Senior Member Array Herknav's Avatar
    Join Date
    Mar 2007
    Location
    Waypoint 0
    Posts
    986
    SIXTO,

    I caught that. Apparently, I was misinformed. I just didn't know if there was an overriding reason to pick the Dissy. (I didn't even know that anybody else made one.)

    I actually like the M4 better, plus it's cheaper. Being restricted to certain kinds of ammo isn't really that appealing, either. Thanks again, gents.
    I would rather wake up in the middle of nowhere than in any city on Earth.--Steve McQueen

  11. #11
    Distinguished Member Array Rexster's Avatar
    Join Date
    Aug 2007
    Location
    SE Texas
    Posts
    1,772
    My aging eyes do MUCH better with the standard rifle sight radius than the carbine/M4 sight radius, and I have been thinking about obtaining a Dissipator upper for my M4-gery for that reason

Sponsored Links

Posting Permissions

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

Similar Threads

  1. Finally got my M4gery back!
    By C9H13NO3 in forum General Firearm Discussion
    Replies: 5
    Last Post: November 21st, 2009, 05:25 PM

Search tags for this page

ar 15 dissipator

,
ar 15 dissipator barrel
,

ar dissipator

,

ar-15 dissipator

,

ar15 dissipator

,
ar15 dissipator barrel
,

dissipator ar

,
dissipator ar 15
,
dissipator vs carbine
,

dissipator vs m4

,
dissipator vs mid length
,
m4gery
Click on a term to search for related topics.