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practical advantages of the mid-lenth upper vrs. carbine upper?

Discussion in 'Rifle Country' started by Fremmer, Nov 14, 2012.

  1. Fremmer

    Fremmer Well-Known Member

    The mid-length uppers seem to command a higher retail price over the typical carbine upper/rifle. They appear to have 2" more barrel and a slightly longer gas system. I read that the benefits of the middy are slightly reduced recoil and lessened wear on the gas system and the bolt. I don't have actual experience with the difference, but am I correct about the advantages of the middy, and more importantly,

    What are the actual advantages of the mid length upper in practical terms for an owner? Can anyone comment on actual data or tests showing a significant advantage over the carbine length for the average owner? Or perhaps your actual experiences with the middy vrs the carbine length? Thanks for the input, I'm just trying to justify the added expense of a mid length gun over the less expensive carbine set up.
  2. Warp

    Warp Well-Known Member

    I have never owned, nor even shot, a mid length. However, from everything I have read I don't think there is a quantifiable, noticeable advantage to the average owner.

    That said, whenever I can afford a second AR (might be awhile), it may very well be a mid length. But I do figure to get more rounds downrange than the average owner, so that "reduced wear" point appeals to me.

    You also (typically) get more rail space, a longer sight radius, and can put your support hand further forward.
  3. nodeal117

    nodeal117 New Member

    They look cooler. What else matters?
  4. highorder

    highorder Well-Known Member

    My wife enjoys shooting my Spikes 14.5" midlength with a Dynacomp.

    My friends carbine gassed 16" with an A2 birdcage is too "sharp" to be pleasant to shoot.
  5. Warp

    Warp Well-Known Member

    Your friend's is probably over gassed. Who made it?
  6. meanmrmustard

    meanmrmustard Well-Known Member

    Less crap in the action, proper dwell time, smoother cycling, and reduced recoil. Better, better, and better.
  7. FMF Doc

    FMF Doc Well-Known Member

    I am not an armorer, but from what I have been told, bery little assuming the barrel length is 16-18". I was told that a carbing with 14-16", mid with 16-18" and rifle with 19-20" have the same "gas dwell time" in the tube. This means that shooting a round in the correct combination of gas tube length/barrel length will yeild about the same effect in regards to cycle operation, speed, and recoil force. At the end of the day, I don't think it really matters. The midlengths in my opion have less felt recoil, but that could be as much a factor of the overall weight increase as it is the gas tube. That's all I got. Hopefully someone who knows a little more will come along and fix anything I got wrong here.
  8. highorder

    highorder Well-Known Member

    It's a S&W m&p15 MOE.

    I agree it's over gassed. Strangely it went back to the factory once for under gassed issues. I wonder if they just reamed the gas port.
  9. Warp

    Warp Well-Known Member

    It isn't fair to blame that on the carbine gas system. That is simply a mid-tier AR manufacturer at work.

    *flame suit on*
  10. Bartholomew Roberts

    Bartholomew Roberts Moderator Emeritus

    The big practical advantages you notice right away are:

    1. Better sight radius
    2. More handguard real estate (easier to use a more forward grip, less hot barrel exposed, more room for rail mounted crap)

    Additional advantages that are more theoretical than practical are a different recoil impulse compared to a carbine and a dwell time that is closer to the original 20" design than a carbine gas on a 16" barrel.
  11. jim243

    jim243 Well-Known Member

    No flame suit needed.

    I prefer the carbine gas system, shorter recycle times. But it is nice to have the longer sight radius if you shoot open sights, but I don't, red dot or scope for me.

    Good luck on your choice.
  12. Fremmer

    Fremmer Well-Known Member

    And that's the rub, mr. Roberts: what are the actual differences in terms of recoil or wear that justify the added expense of the middy for the average owner? Have we had reports of middys lasting significantly longer, or are the advantages pretty much theoretical?

    And I keep wondering why the military, police and others use the carbine instead of the middys. That might be the cost difference, I suppose. That and if you're gonna shoot a middy for dwell time, why not just get 2 more inches from the 20" platform and end the dwell concerns...
  13. meanmrmustard

    meanmrmustard Well-Known Member

    Give it a rest. What would the excuse have been if it were made by Colt? User error?
  14. Warp

    Warp Well-Known Member

    What's your excuse for this rifle?
  15. MistWolf

    MistWolf Well-Known Member

    Middys do not have less recoil. Fire the same ammo out of a 16" carbine length AR and a 16" mid-length AR, both ARs of the same weight and both will have the same amount of recoil.

    There is very little practical difference between the two, assuming both are properly tuned.

    The time it takes the bullet to travel from the gas port to the muzzle makes not a lick of difference. The bullet has cleared the muzzle before the BCG even charges up enough to get moving. What the extra length does is increase the blow down time- that is, the longer the distance from gas port to muzzle increases the time it takes the weapon to drop to atmospheric pressure after the bullet uncorks the muzzle before the gases get to the BCG. Blow down time makes a difference because it's the residual pressure inside the rifle after the bullet leaves that operates the action
  16. meanmrmustard

    meanmrmustard Well-Known Member

    I haven't needed one. Ever.
  17. Warp

    Warp Well-Known Member

    You are the friend being referenced?

    I thought you had a Sport, but sold it?

  18. meanmrmustard

    meanmrmustard Well-Known Member


    Nary you make one. I've owned several Smiths, none had issues. I'm no ones friend, so where is this query leading us exactly?
  19. fatcat4620

    fatcat4620 Well-Known Member

    The carbine the military uses has a 14.5 inch barrel, not a 16 inch like most civilian carbines (which is the point of this debate).
  20. RSR

    RSR Member

    Everyone's liking the midlength upper these days and rightfully so. There is going to be less wear versus the carbine length, but that comes many of rounds down the road. Truth is, shooters and collectors alike will probably never see this wear, so buy the one you want! If you're worried about chamber/bolt/receiver wear, go full length. The AR rifle was built on a 12" gas system and 20" barrel......and a full length shoots best IMHO!!! Best of luck to ya.....

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