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Discussion Starter #1 (Edited)
I am building another AR-15 and am looking at 16" barrels and I am noticing that they are offered in both carbine and Mid length configurations. I have heard that for barrels of this length the ideal is Mid-length, and that carbine will not be reliable, however I have also read people stating that carbine is just fine. What are your guys opinions?

Here is what I know I need:
16" 5.56 barrel with pinned(ideal) low profile gas block (would like to stay under $200-$250)
12" quad rail
.750 shoulder
1:7 twist

What are my options on manufacturers too, that are recommended?

Daniel Defense(may be too expensive), Spikes, CMMG, Rock River Arms, YHM
 

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Both are reliable ... the carbine gas more reliable than the middy, but with a little added recoil. Daniel Defense, RA Mountain Series, Centurion etc are all good choices if you're wanting a CHF barrel ...
 

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Would'nt say that the carbine is more reliable than a middy. Would say that the middy can be more reliable compared to a carbine length. However, the carbine is just alot more common.
The idea behind the middy is that it keeps the gas port the same distance from the muzzle as a 20" barrel.

Assuming a 16" middy and not a 14.5".
 

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Discussion Starter #4
Would'nt say that the carbine is more reliable than a middy. Would say that the middy can be more reliable compared to a carbine length. However, the carbine is just alot more common.
The idea behind the middy is that it keeps the gas port the same distance from the muzzle as a 20" barrel.

Assuming a 16" middy and not a 14.5".
This is kind of what I had been reading, sifting through all the chaff on the net it seems that the conclusion most come to is that a mid-length is easier wear on the BCG and other parts as the pressure is less in a mid-length than in that of a carbine. Which does make sense...

I think I may end up going with either if I can find the barrel I want in stock that is...parts are so difficult to find right now...
 

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I just learned about this myself. The dwell time is what is important when you are talking gas tube lengths.
 

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Would'nt say that the carbine is more reliable than a middy. Would say that the middy can be more reliable compared to a carbine length. However, the carbine is just alot more common.
The idea behind the middy is that it keeps the gas port the same distance from the muzzle as a 20" barrel.

Assuming a 16" middy and not a 14.5".
Not sure I follow your reasoning. A carbine gas system on a 16" barrel has more gas pressure to cycle the BCG than a mid-length system ... period. The idea behind a mid-length gas system was less recoil than a carbine length system, but along with less recoil comes less gas pressure to cycle the weapon; gas port tuning along with cyclic mass are more critical to insure reliability. Both are reliable but I've seen plenty of cycling failures with weak ammo on a mid-length gas system but can count on one hand, similar failures with a carbine length gas system. A carbine length system used to be the standard in the 14.5-16" barreled rifles but the mid-length system is gaining as the new standard gas system for recoil management equating to more accurate follow-up shots. Then again, what do I know ... your mileage may vary? :lol:
 

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Not sure I follow your reasoning. A carbine gas system on a 16" barrel has more gas pressure to cycle the BCG than a mid-length system ... period. The idea behind a mid-length gas system was less recoil than a carbine length system, but along with less recoil comes less gas pressure to cycle the weapon; gas port tuning along with cyclic mass are more critical to insure reliability. Both are reliable but I've seen plenty of cycling failures with weak ammo on a mid-length gas system but can count on one hand, similar failures with a carbine length gas system. A carbine length system used to be the standard in the 14.5-16" barreled rifles but the mid-length system is gaining as the new standard gas system for recoil management equating to more accurate follow-up shots. Then again, what do I know ... your mileage may vary? :lol:
Yes a carbine gas system does have more pressure than a middy. However, the AR15/M16 was originally designed with a 20" gas system and when the 16" carbine rifles came out, the pressure and dwell time/lock up would sometimes cause issues. Thats why heavier buffers, stronger extractor springs and o-ring extractor enhancers came out to help carbine rifles become more reliable.

What buffer are you running on your carbines?? Standard carbine buffer or one of the heavier H buffers??

This is the beauty behind the middy gas system. They typically will run a little cooler than a carbine gas system but more importantly it runs much lower gas pressures. Running lower gas pressures and temps will have less gas port erosion and a better cyclic rate with less port erosion and better bolt life. Without having to have various mods to get it to run reliably.

Overall, the carbine gas system is a bit overgassed, running around 26k psi compared to the rifle gas system running around 13k psi. And a middy in the middle of the two. More gas does NOT mean better. Now running inexpensive, if there is such anymore, 223 that tends to be somewhat weak compared to standard pressure 556 in a carbine gas system tends to run well in most carbines. Though even still , some run them with these bolt mods and heavy buffers to make them reliable.
Bottom line, a carbine system will run with higher pressures, running harder (more wear on parts/parts breakages) with slightly more recoil compared to a middy system. And a rifle system will run with even less wear and tear and less recoil compared to a middy.

The carbine system is the standard. The middy is just an improvement on the carbine idea.

I have had many carbines myself and just a few middys. And other than SBR's, I prefer the middy for its advantages.
 

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Yes a carbine gas system does have more pressure than a middy. However, the AR15/M16 was originally designed with a 20" gas system and when the 16" carbine rifles came out, the pressure and dwell time/lock up would sometimes cause issues. Thats why heavier buffers, stronger extractor springs and o-ring extractor enhancers came out to help carbine rifles become more reliable.
I'm well aware of the original design of the M16/AR15 and it's shortcomings when a shorter barreled rifle came along. Heavier buffers slow cyclic rate and help with over-gassing side effects .... agreed. Stronger extractor springs help with case retention and o-rings help buffer the extractor spring to ease wear ... agreed. Regardless, before this develops into an ARFcom pissing match, let me agree that a mid-length gas system is the best of both worlds on a 14.5-16" barreled AR.

What buffer are you running on your carbines?? Standard carbine buffer or one of the heavier H buffers??
Buffer weight is only one factor in tuning an AR ... a good rule is to adjust weight according to ejection pattern, which is a pretty good indicator of gassing and cyclic rate. Buffer spring rate comes into play as well, along with spring length, but I rarely mess with springs ... if it works, don't fix it. Depending on which rifle I'm referring to and what ammo I usually run in it, along with whether it's suppressed will determine what buffer works best ... generally H or H2 in my 14.5-16's and H3 all the way up to a 9mm buffer in the short barrels(some of those are way over-gassed with or without a suppressor attached). I'm currently building a coyote gun with 18" rifle gas that will run a lightened carrier and a gutted carbine buffer(all weights removed) ... gassed soft, weighted light and really low recoil makes for a fast follow up rifle; opposite of a combat rifle where durability/reliability is primary.

This is the beauty behind the middy gas system. They typically will run a little cooler than a carbine gas system but more importantly it runs much lower gas pressures. Running lower gas pressures and temps will have less gas port erosion and a better cyclic rate with less port erosion and better bolt life. Without having to have various mods to get it to run reliably.
Agreed ... mid-length systems run cooler and lower pressures increase barrel and bolt life, although you'd be hard pressed to "mole" a gas port with a semi-auto rifle; select-fire and a ton of hot ammo and most modern barrels still live to 15-20K rds before port erosion is an issue?

Overall, the carbine gas system is a bit overgassed, running around 26k psi compared to the rifle gas system running around 13k psi. And a middy in the middle of the two. More gas does NOT mean better. Now running inexpensive, if there is such anymore, 223 that tends to be somewhat weak compared to standard pressure 556 in a carbine gas system tends to run well in most carbines. Though even still , some run them with these bolt mods and heavy buffers to make them reliable.
Bottom line, a carbine system will run with higher pressures, running harder (more wear on parts/parts breakages) with slightly more recoil compared to a middy system. And a rifle system will run with even less wear and tear and less recoil compared to a middy.
The carbine system is only "over-gassed" if the gas port diameter is too big? Any reputable manufacturer knows this and will port their barrels accordingly? Nothing was said about more gas being "better"? There is plenty of factory ammo circulating that is weak in comparison to good quality 5.56 ... Wolf, PMC, WWB and older milsurp ammo as examples are weak compared to fresh SS109/M855 or M193. "Though even still , some run them with these bolt mods and heavy buffers to make them reliable." ... I can't imagine buffering up with under-powered ammo? You either need to increase gas pressure or decrease cyclic mass to overcome weak ammo.

The carbine system is the standard. The middy is just an improvement on the carbine idea.
Agreed, although mid-length civilian rifles are the most popular in the AR industry at current ... not many want a carbine gas system in a rifle barrel anymore. Noveske uses a middy system in their 13.7, 14.5 & 16" barrels ... their 18's use the Intermediate gas system; more reliable than the rifle length but still a soft shooter.

I have had many carbines myself and just a few middys. And other than SBR's, I prefer the middy for its advantages.
Most of my rifles are middys ... own a couple shorty carbines and a couple rifle length gassed rifles. I too prefer the mids in most cases.

We could go round and round regarding this subject but let me rephrase my initial statement ... "Both are reliable ... the carbine gas will cycle more reliable than the middy, but with a little added recoil". Fair statement? :wink:
 

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Disagree

Colt is generally considered a reputable manufacturer. However, Colt worked with Crane to come up with the heavier buffer and extractor spring O-ring to make the M4 carbine reliable feeding and extracting. So saying that the gas port diameter is properly sized to correct over-gassed carbine system is incorrect. Pretty sure that Colt played around with the gas port size and still had to come up with those mods.

Now overall if you are going to run a 556 rifle with typically underpowered 223 ammo you could run into problems with either setup.

However, either system will do well for most people if the components are from reputable makers.
 

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Disagree

Colt is generally considered a reputable manufacturer. However, Colt worked with Crane to come up with the heavier buffer and extractor spring O-ring to make the M4 carbine reliable feeding and extracting. So saying that the gas port diameter is properly sized to correct over-gassed carbine system is incorrect. Pretty sure that Colt played around with the gas port size and still had to come up with those mods.

Now overall if you are going to run a 556 rifle with typically underpowered 223 ammo you could run into problems with either setup.

However, either system will do well for most people if the components are from reputable makers.
Disagree all you like ... the fact remains that if carbine gassed AR's were so prone to reliability issues, they'd be phased out of any barrel/rifle manufacturers lineup on any barrel over 12.5" long, in favor of middy gas; clearly that's not the case? Colt is a reputable manufacturer but not the "holy grail" of AR's anymore (hasn't been for some time) ... there's no shortage of manufacturers that have taken the design and improved it dramatically; cold hammer forging, ferritic nitrocarburizing, .223 Wylde chamber, button rifling, hybrid gas lengths(intermediate), adjustable gas blocks and the list goes on. I've built plenty of carbine gassed rifles that were not over-gassed at all and ran perfect with a standard weight buffer(2.9-3oz) ... this due to proper gas port dimensions. Once again, I've seen more mid-length gas systems have under-gassing cycling issues than carbine systems have over-gassing issues, especially with the 14.5 barrels, regardless of manufacturer ... that experience is why I stated "Both are reliable ... the carbine gas more reliable than the middy, but with a little added recoil.". Colt working with Crane on heavy buffers and extractor spring O-rings was directed at the M4 carbine ... a 14.5", direct-impingement, select-fire rifle that has a lot more stress on it's internals than any civilian, semi-auto rifle will ever have; apples and oranges pertaining to the OP's original question and my earlier statement?

Apologies for the derailment of your thread s4mur41h4x0r ... I'm done here. :wink:
 

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Discussion Starter #12
Disagree all you like ... the fact remains that if carbine gassed AR's were so prone to reliability issues, they'd be phased out of any barrel/rifle manufacturers lineup on any barrel over 12.5" long, in favor of middy gas; clearly that's not the case? Colt is a reputable manufacturer but not the "holy grail" of AR's anymore (hasn't been for some time) ... there's no shortage of manufacturers that have taken the design and improved it dramatically; cold hammer forging, ferritic nitrocarburizing, .223 Wylde chamber, button rifling, hybrid gas lengths(intermediate), adjustable gas blocks and the list goes on. I've built plenty of carbine gassed rifles that were not over-gassed at all and ran perfect with a standard weight buffer(2.9-3oz) ... this due to proper gas port dimensions. Once again, I've seen more mid-length gas systems have under-gassing cycling issues than carbine systems have over-gassing issues, especially with the 14.5 barrels, regardless of manufacturer ... that experience is why I stated "Both are reliable ... the carbine gas more reliable than the middy, but with a little added recoil.". Colt working with Crane on heavy buffers and extractor spring O-rings was directed at the M4 carbine ... a 14.5", direct-impingement, select-fire rifle that has a lot more stress on it's internals than any civilian, semi-auto rifle will ever have; apples and oranges pertaining to the OP's original question and my earlier statement?

Apologies for the derailment of your thread s4mur41h4x0r ... I'm done here. :wink:
No apology necessary, this has been extremely insightful and was exactly the info I needed. Thank you for sharing your knowledge with us!
 

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No apology necessary, this has been extremely insightful and was exactly the info I needed. Thank you for sharing your knowledge with us!
I hope this debate hasn't dissuaded you from a mid-length gas system barrel as that was definitely not my intent ... most of my AR's are middy gas for a reason;100% reliable function with less recoil/heat/pressures is the best of both worlds. My original statement regarding reliability of carbine gas was kind of vague ... what I should have said to avoid the long, drawn out banter was that "a carbine gas length barrel is less apt to require ANY tuning to insure reliability, with sub-standard powered ammunition, but is harder on the rifle's other components due to the effects of increased gas pressure". :mrgreen:
 
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