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Posted: 9/17/2008 5:43:53 AM EDT
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What is the real advantage to having a mid-length gas system over a carbine system? Is it enough to really make a difference? Thanks. |
A Search (the button above between the "Newest Topics" and "Archive" buttons) for "mid-length" in the AR15 Community within the past 30 days yields a bunch of (possibly informative) threads:Why Buy A Mid-Length? The advantages for me are: 1) More handguard real-estate 2) Better reliability (not that the carbine system is unreliable, the middy is just "more" reliable) 3) Softer recoil impulse (although I really can't tell the difference) 4) Longer sight radius (moot, when using a red-dot) 5) Looks YMMV, of course. 
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All, pluses and no minuses. Unless I run a a bbl shorter than 14.5" I use middys. 
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Owning both, I can tell you there is not much difference between the two. It's more about what's the latest trend on AR15.com. A couple years ago 1:9 twist was in, now it's taboo. This year Noveskse rifles are hand crafted from God, next year that might not be the case. I agree that the midlength is often times more aesthetically pleasing to the eye. However, the recoil difference is so marginal that I wouldn't consider it a selling point at all. And EVERY time this thread comes up about the midlengths being more reliable than the carbines, I ask the same question, and I never get an answer: Does ANYONE have any evidence (i.e a test with QUANTIFIABLE RESULTS) to demonstrate that midlengths are in fact more reliable or last longer than carbines? I've shot thousands upon thousands of rounds through both my midlength and carbine and if I showed you the FCG, buffer, and BCG of both rifles I would bet the farm that not even the most knowledgable internet commando could tell them apart. |
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You'll see that I pretty much agree with you as most of the comments in my above post include a caveat, except for the first item relating to ergonomics. There is a graphic somewhere out there (I'll have to look for it) with dwell times, chamber pressure curves, etc (quantifiable enough for you?  ) showing that basically, carbine < middy < rifleIn the end, get what fits your intended purpose, budget, etc. 
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I agree. I think it would take a metallurgist to really decipher the chart and actually prove that midlength lasts longer. I am not doubting that it is true, I just haven't seen a test that proves it. |
Here are the charts you were talking about, it's tacked in the Troubleshooting forum. The graphs info are accurate but the authors explanation are not exact because it's just been copied from another post from another site. How it Works - The AR Gas Operation and How Everything Works in Harmony - thread link I agree with the other replies about the slight differences and would also want to add that in a lifetime of the middy it would eat less bolts than the carbine gas system. That info are from numerous past threads here from members that experienced it, I have not actually seen it because I only had my middy for only three years but I'm a long time carbine user for 22 years now. I know from experience between the rifle gas system and the carbine that the carbine eats more bolts, and since the midlength is closer to the rifle it's possible that statement about the middy consumes less bolts are probably true. |
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www.ar15.com/forums/topic.html?b=3&f=118&t=386126 couple more threads from a month or two ago that I can't find... The advantages are that from both human and mechanical engineering the midlength is a more optimal configuration for a 16" barrel length. With a direct gas system like the AR has, matching the gas system length to the overall barrel length is critical to optimum operation of the firearm. Human: Longer sight radius, more handguard length, smoother operation. Mechanical: relationship of pressure to dwell time much closer to optimum than carbine length gas system, so less wear, higher reliability, reduced heat stress on gas system components, reduced gas port erosion. |
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