Firearm & Gun Forum - FireArmsTalk.com > Long Guns > Auto & Semi-Auto Discussion > AR-15 Discussion > WHY HAVE DIFFERENT LENGTHS? ie. carbine, mid, rifle.

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Old 11-28-2011, 05:02 PM   #1
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Default WHY HAVE DIFFERENT LENGTHS? ie. carbine, mid, rifle.

What are the main reasons for different length AR's? What are advantages/disadvantages of each?

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Old 11-28-2011, 05:17 PM   #2
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carbine length is actually designed for a 14.5 inch m4 military barrel not the 16 inch civvy carbines. midlength works MUCH better on a 16" barrel much better smoother recoil impulse. rifle length is even smoother than mid. thats why the first m16 barrels were 20". the shorter you go the more difficult it becomes to maintain a AR15. you get more parts breakage due to the increased forces of the shorter carbine tube.

i just dont see the point of a carbine length tube on a 16" barrel. it doesnt make sense to me.

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Old 11-28-2011, 05:47 PM   #3
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So I'd want a rifle length on a 16" barrel ideally?

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Old 11-28-2011, 08:07 PM   #4
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Broke, did you read what JonM said? Though none of us know what you want he clearly stated what most people consider the best gas length for the 16" barrel. Clue: he didn't say rifle length or carbine length.

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Old 11-28-2011, 08:12 PM   #5
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Then he said rifle is even better. So now I'm confused.

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Old 11-28-2011, 09:19 PM   #6
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rifle length on a 16" doesnt allow enough room at the end to give the gas time to work the action you end up with short stroking problems. mid length is the longest that works reliably. you MIGHT get away with a rifle length running with little trouble if you use a suppressor 100% of the time.

on a 16" midlength is ideal. the reason you dont see it offered a lot is because of the popularity of the carbine look and most of the aftermarket rail systems are carbine length. midlength is becoming more popular.

if your going 20" then full rifle length. its all got to do with gas pressure. the closer the gas port is to the chamber the higher the pressure is delivering more force to the gaskey on the bolt body. for carbines to work right you have to make the gas port smaller to reduce the ammount of gas. with a smaller gas port you run into reliability issues with the port getting clogged and under powered ammo not having enough ooomph.

mid length gives you the ability to operate at a larger gas opening smoothing out the impulse and rifle does an even better job. when you see people having problems with cheap ammo its always carbine gas systems. rifle and mids are more reliable.

anyway those arent hard fast rules just kinda guildlines. there are carbines that will run thousands of rounds no issues on the cheapest ammo out there. there are rifle length that will have problems with prmium ammo. its just a general idea of the theories behind and why there are different lengths.

i personally dont see a purpose in the civvy non-nfa non-ar pistol world for carbine gas tubes

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Old 11-29-2011, 03:37 AM   #7
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This question seems to have come up at least a couple times here recently.

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Old 11-29-2011, 03:53 AM   #8
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Quote:
i personally dont see a purpose in the civvy non-nfa non-ar pistol world for carbine gas tubes
In a world where engineers make the rules function would always win out over form but I suspect that the aestheticly appealing carbine length handguards drive much of the popularity of the carbine length gas systems. Opposite applies to the "old school" look of the rifle length systems. JMHO...
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Old 11-29-2011, 04:35 AM   #9
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I would disagree that the carbine length was developed for the 14.5" barrel as the 16" carbine pre-dates the 14.5" by about 30 years.

I do not see a problem with a 16" carbine length set up. I have run many thousands of rounds through mine w/o any breakage. I run a "H" buffer and enhanced extractor spring.

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Old 11-29-2011, 11:14 AM   #10
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Quote:
Originally Posted by robocop10mm
I would disagree that the carbine length was developed for the 14.5" barrel as the 16" carbine pre-dates the 14.5" by about 30 years.

I do not see a problem with a 16" carbine length set up. I have run many thousands of rounds through mine w/o any breakage. I run a "H" buffer and enhanced extractor spring.
What does H buffer mean?

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