CAR or mid length AR

[Firebricker]

I was checking on 16" CAR upper reciever assembly's and a supplier suggested going mid length. He said the couple extra inches of gas tube would make it cycle smoother.

But I have also been told a heavier buffer will do the same thing. I'm totally new to AR's so I have no idea how big of a differance it would make.

So I'd like to know what you guy's think. I like the look's of the CAR length handguards better but that's no big deal much more concerned with which would better. Thank's in advance FB

[Eagles6]

It's commonly said that the 5.56 round is optimal out of a 20 inch barrel and that problems that the military have is because they use the shorter barrel on the M4s.
Don't know if it's true but something to check out on the AR15 boards.

[GabbyM]

I personally loath 16 inch barrel AR's. If length is that big a deal think about a 20" barrel with no flash hider. Deleting the flash hider will reduce muzzle blast off to the sides and I believe back at the shooter as well. All while cutting an inch or so off the O.L. 20 inch AR's are carbines after all not a rifle.

16” barrel AR's are a recipe for hearing loss. Due to horrible muzzle blast. As I've stated before on this forum I have ringing of the ears and it is not a good thing. Yes this does give me an attitude. Mine I think is factory work. My father thinks his is from straight pipe tractors but it may have been M2's out the side door of H17's. He'd never blame anything on the corps as it's just not the way old Marines think.

What I'm getting at is don't think you can shoot a machine pistol with a two foot muzzle flame and not suffer the effects of that blast. Put a barrel on that thing.

FYI : Shotguns reach max velocity within 12 to 14 inches of barrel length. We use long 28 to 30 inch barrels to save us from self mutilation. In other words the long barrels on shotguns are only there as a hearing protection device. Well that and they are much more gentlemanly in presentation.

2nd FYI: Don't anyone give me any of that hooplaw about wearing ear plugs. They only afford a margin of protection and that's if you think you will never shoot nine shots in your life without them. I despise 16" barrel rifle caliber guns. Your opinion may vary. I wore 17 db ear plugs in the factory but sound levels were past the point 17 DB would save you 100%. The old guys I worked with whom had worked through the forties and fifties with no hearing protection all wore hearing aids so they could talk to people. I mean all of them not just a few.
Head phones or ear muffs should work to protect I'd think. Electronic head phones are the best invention in shooting sports in fifty years.

My drum is about worn out now.

[deltaenterprizes]

If I plan on having to carry it I want the 16'', for the range and plinking the longer barrel will work.

[Combat Diver]

As stated the long gas tube was designed for the 20", however the carbine gas tube was designed for a 10.5/11.5 for the XM177 submachine gun. I never had a problem with a 14.5" M4A1 for the 13 years that I carried one in service (95-08). My personnel AR has a pinned 14.5" bbl by going to a 16" with full auto can lead to trouble but in semi not really a problem if set up properly. It all boils down to personal preference in my opion.

[StarMetal]

There are three gas tube lengths...the rifle, the carbine, and mid length.

The short barreled AR's run pretty good. It's when you go full auto or put a can on them that things change.

I wouldn't add a heavier buffer because it slams the bolt/carrier group harder against the barrel extension.

The short barrel will be louder and that is true of any short barrel rifle. The flash hiders aren't compensaters and don't direct the gas back towards you, but they do spread it around a making the blast louder. With a particularly loud firearm you should wear ear plugs and muffs both. Some people don't realize that with just wearing earplugs sound also travels to inside the ear through the skull bone structure. This is where muffs are better as they cover a wider area around the outside of the ear.

[dualsport]

All good advice. Ear plugs AND muffs is the ticket when shooting. At the range even if your barrel is longer the guy next to you will show up with something gawdawful that pierces your eardrums. On the length question, ar15.com is chock full of ar info. You don't want tinitus(ringing), once it starts that's it, it never stops, believe me it's unpleasant. Long term exposure to loud noise will do it too, but gunfire and explosions can get you there real quick. My son's a combat vet, almost daily exposure for months, his ears are as bad as mine, I'm 56, he's 24. I've known people who's lives were literally ruined by tinitus. Protect your ears, always.

[mike in co]

It's commonly said that the 5.56 round is optimal out of a 20 inch barrel and that problems that the military have is because they use the shorter barrel on the M4s.
Don't know if it's true but something to check out on the AR15 boards.

i like that....lol

"commonly said"

right by who ????

never heard it before in my life.....

[mike in co]

I was checking on 16" CAR upper reciever assembly's and a supplier suggested going mid length. He said the couple extra inches of gas tube would make it cycle smoother.

But I have also been told a heavier buffer will do the same thing. I'm totally new to AR's so I have no idea how big of a differance it would make.

So I'd like to know what you guy's think. I like the look's of the CAR length handguards better but that's no big deal much more concerned with which would better. Thank's in advance FB

it aint my gun its yours...what do you plan on doing with it ???

i shoot 17.5 and 18s from rifle handguards.

just got two 16's in carbine config.

its more about your plans than anything else.

mike in co

[mike in co]

. 20 inch AR's are carbines after all not a rifle.



sorry but wrong.
20" m16's/ar15's are RIFLES
16"s are carbines.

the term moves with the times.
in 1891 the 31" bbls were rifles, and then cut down to high 20s as rifles, while 38's with 20" bbls were carbines.

the m14 and garand are both 22( iirc) as rifles.

things change..the definition of rifle and carbine is a moving target.

generically speaking, a carbine is a shorter bbl version of the current rifle.

if a 20 ar is a carbine , what is a 14.5 " ??
mike in co

[StarMetal]

i like that....lol

"commonly said"

right by who ????

never heard it before in my life.....

Eugene Stoner

[Firebricker]

Thank's to you all for your input. Looks like it's not going to make a huge differance either way. The gun's mainly going to be a plinker and to carry when hanging tree stands for ground hogs. So it's just going to be a handy carbine that's fun to shoot.

This AR will also replace my mini-14 I traded off. Leaning towards the RRA mid-length it will be a week or two before I order so I still of time to research and think it over.

Thanks again, FB

[GabbyM]

sorry but wrong.
20" m16's/ar15's are RIFLES
16"s are carbines.

the term moves with the times.
in 1891 the 31" bbls were rifles, and then cut down to high 20s as rifles, while 38's with 20" bbls were carbines.

the m14 and garand are both 22( iirc) as rifles.

things change..the definition of rifle and carbine is a moving target.

generically speaking, a carbine is a shorter bbl version of the current rifle.

if a 20 ar is a carbine , what is a 14.5 " ??
mike in co

I call a 14.5 inch barrel a pistol. Just like the Germans called the MP-40 a machine pistol. It's all in a name that's somewhat meaningless but for description. In my eye a 20” barrel is a carbine barrel. We still call Win 94's and Marlin 336's with 20” a carbine don't we. Of course if you tell some one you have an AR carbine they'll think you are talking about a 16” barrel. So we call the 20” a rifle. But it's still a carbine. Most descriptive term for the Army M4 is probably to just call it an M4 and forget the fine description.

[Moonie]

My son and I built a 16" AR and went with the mid-length gas tube. We fired it side by side with one with a carbine length, the mid-length cycled smoother and had less recoil, noticeably less, everything else was the same, weight was about the same, same flash hider.

I'd go mid-length again in a heart beat.

[StarMetal]

I call a 14.5 inch barrel a pistol. Just like the Germans called the MP-40 a machine pistol. It's all in a name that's somewhat meaningless but for description. In my eye a 20” barrel is a carbine barrel. We still call Win 94's and Marlin 336's with 20” a carbine don't we. Of course if you tell some one you have an AR carbine they'll think you are talking about a 16” barrel. So we call the 20” a rifle. But it's still a carbine. Most descriptive term for the Army M4 is probably to just call it an M4 and forget the fine description.

That's because the 94's and 336's were first long barreled rifles, then they cut the barrels down to make them handier...thus carbines.

The German MP38 had a much much shorter barrel on them then 14.5 inches. Germans also had a thing not to call firearms like those submachine guns.

An AR15 pistol is marked such by regulations from the ATF and you can't use the lower receiver for anything else.

[mike in co]

I call a 14.5 inch barrel a pistol. Just like the Germans called the MP-40 a machine pistol. It's all in a name that's somewhat meaningless but for description. In my eye a 20” barrel is a carbine barrel. We still call Win 94's and Marlin 336's with 20” a carbine don't we. Of course if you tell some one you have an AR carbine they'll think you are talking about a 16” barrel. So we call the 20” a rifle. But it's still a carbine. Most descriptive term for the Army M4 is probably to just call it an M4 and forget the fine description.

yes but you are not the batf...

a 14.5 with a fixed flash hider is still a rifle by batf, and a carbine version of an ar.( WE WERE TALKING ABOUT RIFLES AND CARBINES, NOT PISTOLS so dont take my question out of context)

now you want to mix apples and oranges.....
go read what star said....

a long bbld 1891 is a rifle, when cut to 20 its a carbine( with in its family)

a lever gun in 24 inches is a rifle and when shortened to 20/16 its a carbine( in its family)

an ar began life as a 20 rifle( ask uncle sam...its a rifle), when shortened to 16 they are carbines as are 14.5's with permanent flashhiders to make 16".......less is a pistol, legal or otherwise.

again calling it what you want, dont make it so...facts are facts.

mike in co

[Storydude]

Please show me where BATFE makes a distinction between pistol, shotgun, rifle and CARBINE.


Last time I looked in my Big Blue book, there were 3 classes of firearm.
Pistol
Long gun
Other.

Pistol is no buttstock, and marked as such.

Long gun is rifle/shotgun in ANY length beyond 16" for centerfire and 18" for shotgun.

Other is a bare receiver, NOT made into a firearm as of yet.

no Carbine designation found.

[StarMetal]

Please show me where BATFE makes a distinction between pistol, shotgun, rifle and CARBINE.


Last time I looked in my Big Blue book, there were 3 classes of firearm.
Pistol
Long gun
Other.

Pistol is no buttstock, and marked as such.

Long gun is rifle/shotgun in ANY length beyond 16" for centerfire and 18" for shotgun.

Other is a bare receiver, NOT made into a firearm as of yet.

no Carbine designation found.
Assembling a short barreled AR-15

Under U.S. firearms laws, only the lower receiver of the AR-15 is considered a firearm and subject to purchasing restrictions. (This is not universally the case with rifles. On some other rifles, such as the FN-FAL (http://en.wikipedia.org/wiki/FN-FAL), the upper is the serial-numbered part, and thus the firearm.) The upper receiver assembly is simply considered a part, and may be freely purchased and mail-ordered in most locations. This is a very attractive feature for enthusiasts, who can purchase a number of upper receivers (often in different calibers) and interchange them with the same lower receiver. However, one must be thoroughly familiar with firearms laws before doing this as it is possible to make a configuration that requires a special approval or tax stamp or a configuration that is illegal under state law.
For example, an 11" barrel with only a pistol grip is a legal handgun in most locations. Adding a shoulder stock to an AR-15 with a barrel shorter than 16" would constitute constructing a Short-Barreled Rifle (SBR) under NFA rules - subjective to a $200 tax stamp. Constructing an AR-15 pistol using a lower receiver which had already been designated a rifle or described as such on an ATF form 4473 would constitute the construction of a firearm, since the pistol was constructed from an existing rifle. It is a felony to assemble, possess, or transfer such a weapon without obtaining ATF approval (subject to state approval) and the corresponding $200 tax stamp. If a lower receiver is designated and transferred as a pistol, you are disallowed from installing a butt stock or a forward pistol grip, as the former would render it an SBR (short barreled rifle), with the latter effectively constructing an AOW (Any Other Weapon) requiring the ATF approval and tax stamp.

[Storydude]

SBR is still classed as a Rifle. not Carbine.

Just like SBS is still a shotgun, unless it's a DD or AOW.

[StarMetal]

SBR is still classed as a Rifle. not Carbine.

Just like SBS is still a shotgun, unless it's a DD or AOW.

It's classified that way because it has a rifle receiver such stamped. Understand now? It's sort of the same with TC Contenders and rifles. You run into legal problems with them switching frames in certain manners. The military names the M4, for example, as a carbine, not a rifle.

If you build an AR15 on a M16 lower receiver, it's classified as a Class III gun, even though it's a semi automatic rifle.

Oh almost forgot, not knocking you or upset or anything, Just seeing if you understand what I'm saying.

[Storydude]

Still doesn't change the fact it could be stamped "purple" and the ATF still calls it a rifle.

the ATF has no legal description or definition of "carbine" as Mike insinuated to above.

Even a Transferrable is classed as a rifle, on the 4473 form, when it's clearly on the NFA list and Class 3 taxable.

[StarMetal]

Here's an AR15 pistol:

http://www.machinegundealer.com/AR15bPistol-leftside.jpg

Do you see any way to hold it other then as a pistol? No
To further complicate things the ATF says putting any rifle holding device on it, such as stock or forearm then constitutes it as a short barreled rifle. Of course the military would call that a carbine.

If it was a pistol the lower will be stamped that way. If it was a rifle the lower will be stamped that way. What are you not understanding.....they do mark them they don't have to color them.

[Storydude]

I think you just cleared that up for yourself.

3 types of firearms to be recorded on a 4473.
Long gun
Pistol
Other.

No carbine found.

Ergo, Carbine is not an accepted definition of a firearm in the eyes of the ATF.

It's a pistol, Long gun or Other.


I'd have my rear in a sling next audit I put "carbine" on my side of a 4473.

[StarMetal]

That's correct about the ATF and it's for record keeping. It's not in the eyes of the Army. So I reckon if you're in the Army and your superior tells you to go get a carbine and bring it back to him that you would pick up a rifle, right?

We can take up a petition and request that ATF that we want them to rewrite the 4473 that we want a specific description of or firearms arms on there...such as.....Model 94 Winchester Carbine with 20 inche barrel, Model 94 Winchester Carbien with 16 inch barrel, Model 94 Winchester Rife with 24 inch barrel, Model 94 Winchester Rife with 26 inch barrel. I'm sure they will oblige us.

[Storydude]

That's correct about the ATF and it's for record keeping. It's not in the eyes of the Army. So I reckon if you're in the Army and your superior tells you to go get a carbine and bring it back to him that you would pick up a rifle, right?

We can take up a petition and request that ATF that we want them to rewrite the 4473 that we want a specific description of or firearms arms on there...such as.....Model 94 Winchester Carbine with 20 inche barrel, Model 94 Winchester Carbien with 16 inch barrel, Model 94 Winchester Rife with 24 inch barrel, Model 94 Winchester Rife with 26 inch barrel. I'm sure they will oblige us.

Mike didn't say anything about the Eyes of the army, just the Eyes of the BATFE.

I know common definition of a carbine is a barrel sub 20". Matters not if it was based on a longer platform.

an AK is a Carbine.
An SKS is a rifle.
An AR platform can be both, depending on barrel length.



ATF still says all of those are "Long guns"(assuming AR has a provision for mounting a buttstock, if not, that AR is a pistol)

[mike in co]

Please show me where BATFE makes a distinction between pistol, shotgun, rifle and CARBINE.


Last time I looked in my Big Blue book, there were 3 classes of firearm.
Pistol
Long gun
Other.

Pistol is no buttstock, and marked as such.

Long gun is rifle/shotgun in ANY length beyond 16" for centerfire and 18" for shotgun.

Other is a bare receiver, NOT made into a firearm as of yet.

no Carbine designation found.

sorry, i did not see the spot where i said batf defined a carbine.......

[Storydude]

http://castboolits.gunloads.com/showpost.php?p=934219&postcount=16
First line in this post.

"You are not the ATF"

ATF makes no definition of Carbine, so what he calls it is immaterial to what it's defined as.

[mike in co]

http://castboolits.gunloads.com/showpost.php?p=934219&postcount=16
First line in this post.

"You are not the ATF"

ATF makes no definition of Carbine, so what he calls it is immaterial to what it's defined as.

another person that cannot stay in context........

lets look again
we are talking about carbines and rifles....
the respondents says something is a pistol...an out of context answer to the subject, and now you claim i said.....
i said he was not the batf...thats all and WENT BACK TO THE SUBJECT...RIFLES AND CARBINES.
i clearly stated that it was a rifle, but the carbine version.

THE SUBJECT is one mans aged opinion that only long bbls are rifles and all else is a carbine, thus the m16a2 is a carbine by him, but not by the army, the air force, the navy , the coast guard and the marines, and the nearly everyone else in this modern day.

it is a moving definiton...he has not moced with the times ,plain and simple.

mike in co

[mike in co]

Still doesn't change the fact it could be stamped "purple" and the ATF still calls it a rifle.

the ATF has no legal description or definition of "carbine" as Mike insinuated to above.

Even a Transferrable is classed as a rifle, on the 4473 form, when it's clearly on the NFA list and Class 3 taxable.

so i should thank you for proving the other guy wrong...there are NO CARBINES....
ARE YOU WILLING TO PUT YOUR BUTT ON THE LINE AND CLAIM THERE IS NO SUCH THING AS A CARBINE........?????
( or would you rather get back in context and on subject, is the m16a2 a rifle or a carbine ?)


YOU ARE FUNNY
again i suggest you stay on topic IN CONTEXT

[Storydude]

so i should thank you for proving the other guy wrong...there are NO CARBINES....
ARE YOU WILLING TO PUT YOUR BUTT ON THE LINE AND CLAIM THERE IS NO SUCH THING AS A CARBINE........?????
( or would you rather get back in context and on subject, is the m16a2 a rifle or a carbine ?)


YOU ARE FUNNY
again i suggest you stay on topic IN CONTEXT

According to the ATF, there IS no such thing as a Carbine.

It's Long gun, Pistol or Other.

Are you suggesting I call in a 4473 and say "carbine" when asked what type of firearm it is?

I already know what that'll tell me.

"that is not a valid answer. Please repeat firearm type"


An M16A2 is a rifle. M4 is a "carbine LENGTH" rifle.

Common vernacular aside, in my business, if the ATF says it's something, that's what it is. Regardless of what the common name for it is.

[StarMetal]

Anything that isn't a pistol or shotgun is a long gun. Carbine is a subcategory of a long gun. Maybe the ATF should change it to only require gun? After all they have more details on it in other blocks and the serial # so they very well know what it is.

[Multigunner]

According to the ATF, there IS no such thing as a Carbine.

It's Long gun, Pistol or Other.

Does the ATF actually say this? Or is it simply a matter of their not making a distinction between rifles and carbines?
The AFT is regulatory, not the end all and be all in defining firearms nomenclature.

Pre to early 20th century a rifle with barrel as long as 22 inches would be a carbine. In France the term Carabin meant any handy rifle regardless of length, a sporting rifle as long as a Pennsylvania rifle would still be a carabin as opposed to the musket and musketoon which later was more nearly carbine length.
The Gendarme Carbine was any short rifle that was used as a easier to hit with substitute for the handgun. That definition is the one applied to our US M1 .30 Carbine.
The British considered SMGs to be "Machine Carbines".

The major user of the M4 Carbine is the US military so their terminology trumps all in that case.
The M16 Rifle is by civilian sporter terminology a short rifle, 20-22 inch. Before 1903 and for some time afterwards rifles with barrels shorter than 26 inches would be considered as "Short Rifles". Classic example is the Short Magazine Lee Enfield, with short denoting barrel and overall length compared to the standard Lee Enfield. British publications often labeled the 1903 Springfield as a Short Rifle as well, though both are now well within the modern definition of a full length rifle.

PS
The shorten tubes of the M4 carbine are responsible for greatly reduced stopping power and wounding effects compared to the M16. This has been the subject of numerous studies run by the military. Its a fact not in doubt.
The shorter barrels can cut up to 500 fps off the striking velocity at any range the M4 is used.

I like the handy qualities of the short 16 inch CAR Sporter, I've had the pleasure of firing a prime Colt manufactured example of this little carbine years ago. But its penetration is laughable and theres no wind bucking ability to speak of.
Carbines of this class are more deadly than a 9mm SMG but a long way from being a good substitute for a battle rifle.


A 5.56 cartridge with bullet and powders re-engineered practically from the ground up specifically for the 14 inch barrel might allow better efficiency from the M4, and those who own these SBR or AR pistols and handload for them should make the results known.

[Storydude]

Anything that isn't a pistol or shotgun is a long gun. Carbine is a subcategory of a long gun. Maybe the ATF should change it to only require gun? After all they have more details on it in other blocks and the serial # so they very well know what it is.

I feel they should go to pre 68 rules, but they don't listen to me.[smilie=1::drinks:

[StarMetal]

I feel they should go to pre 68 rules, but they don't listen to me.[smilie=1::drinks:

Folding up the ATF would be a good idea. Look at the money the government would save.:drinks:

[mike in co]

According to the ATF, there IS no such thing as a Carbine.

It's Long gun, Pistol or Other.

Are you suggesting I call in a 4473 and say "carbine" when asked what type of firearm it is?

I already know what that'll tell me.

"that is not a valid answer. Please repeat firearm type"


An M16A2 is a rifle. M4 is a "carbine LENGTH" rifle.

Common vernacular aside, in my business, if the ATF says it's something, that's what it is. Regardless of what the common name for it is.

well as long as you are going to stayOFF TOPIC... DUH

THERE IS NO SUCH THING AS THE ATF....

WAKE UP
you are in the past like the other guy.

again , back on topic, its about his definition of rifle and carbine,....not the BATF..

READ MY LIPS , it is not about the batf...that only came up when he went OFF TOPIC.
THE TOPIC IS """" what is a carbine, what is a rifle...as refers to the military m16 with a 20" bbl...that would be an m16a2"""""""."
end of subject
notice no reference to any batf.......

and thank gawd...you answered that very question:

"An M16A2 is a rifle. M4 is a "carbine LENGTH" rifle."

its over....you said it...thanks
mike in co

[GabbyM]

Mike the topic is what the OP posted. He was looking to chose between a CAR-16” and a mid length. Mid lengths have 16 or 18 inch barrels. I simply tried to point out that a 20” barrel is plenty short and is in fact a carbine length rifle already. Then I mentioned if you get a 20" with no flash hider it's approximately as short as an 18" with attatchment. All on topic as far as I can tell. I seriously do not care what the Army labels M16's as. We are after all taking about a bunch of politicians and in the case of the AR-15 the Wiz Kids. Before that salesman called the AR whatever they thought would make the sale of Stoner's new thing. Salesmen do not define mechanics any more that Rolling Stones Reporters decide who is a good General.

A 20” barrel is a carbine length barrel. An 11 ½ inch M4 barrel is a pistol length barrel. You may have an argument point as to weather a 14.5” is a carbine or pistol length as the line is blurred. There has never been an M16 battle rifle issued. I don't care what they call it. I like my AR's very much but they are not battle rifles. They are carbines. Perhaps the best carbine ever made. No amount of BS will change the facat that no 5.56mm is a battle rifle. An AK 47 is also not a battle rifle. Please do not retread how I'm not keeping up with the times. BS is BS. I do not care how many years it goes on for.

Also I stated quite clear the reason I loath shorty M16's is my hearing loss tinnitis condition. In addition to hearing 48 db ring all the time it makes one more sensitive to the muzzle blast. Again I do not think it's from my shooting sport but rather factory work. Sensitivity to muzzle blast is not psychological it's a physical thing. It actually hurts a tiny bit. Over and over. When one of the LEO's shows up at the range and there are twelve benches but they set up next to you since they are sociable nice guys looking to have a good time. It's hard since I like to talk myself and like them but can't stand the issue blasters they show up with. So I just tough it out. Again the battery powered head phones are great items. But just like shooting prairie dogs all day you are beat to a pulp after an afternoon of that M4 blast. It's kind of like a drug with side effects. Supposedly there are benefits but do they out weigh the side effects. When I read a post from a man trying to decide what length AR barrel to shoot it's my opinion he should go with a full 20”. I've stated reasons why I have that opinion.

[Multigunner]

The assault Rifle concept certainly muddied the waters.
Its like the Karabiner 98a being a Carbine while the identical length Kar 98 is a battle rifle.
The concept of what makes a rifle is in flux. OAL went out the window with the first Bull Pup conversions of the Lee Enfield and Springfield 1903 rifles. Now some full length barreled rifles are no longer than some pistol carbines.

[Ickisrulz]

For anyone considering building or buying an AR, I would suggest research at
m4carbine.net

The guys who frequent there run their guns hard and eat sleep and breath the AR platform. There's lots and lots of good information.

[GabbyM]

assault rifle would be a good description of an M16. Term is so loaded down with social baggage I shrink from using it.

30 caliber US M1 Carbine has an 18” barrel. M1 30-06 Battle Rifle it worked next to had a 24" barrel. US Army rejected a shorter barrel version due to muzzle balst. Springfield Armory marketed a Tanker M1 with short barrel back around the 1980's but it was never an issued rifle. Back then the Army had more sense that that.

[Moonie]

Ok, not to butt in but the original topic was about the position of the gas port, NOT about length of the barrel.

Carbine length might be better for shooting boolits (higher pressure, more dwell time with fast pistol powders) but mid-length will be easier on the gun and shooter due to reduced bcg velocity from lower pressure/dwell time at the port.

Guys come on, the fighting is really not necessary.

[Multigunner]

assault rifle would be a good description of an M16. Term is so loaded down with social baggage I shrink from using it.

30 caliber US M1 Carbine has an 18” barrel. M1 30-06 Battle Rifle it worked next to had a 24" barrel. US Army rejected a shorter barrel version due to muzzle balst. Springfield Armory marketed a Tanker M1 with short barrel back around the 1980's but it was never an issued rifle. Back then the Army had more sense that that.

The Army had experimented with a shortened Springfield between wars, the Bushmaster with 18 in tube. It failed for the same reasons the Tanker Garand failed, excessive muzzle blast.

A sort barrel is theoretically as accurate if not more accurate than a longer barrel, in fact some match grade air rifles use a very short rifled bore insude a barrel jacket which is only there to provide a longer sight radius.

The lack of accuracy of full power short barrel rifles comes from two main effects, lower velocity with the same rate of twist as the long barrel, and greatly increased deletrious effects of any abnormality near the muzzle. The greater the muzzle blast the more that blast can contribute to destabilizing effects of a bad crown or worn lands at the muzzle.

Back to the gas port position
A friend constructed entry weapons for LEO and civilian agencies.
He prefered a shortened AR 15 with full length handguards and gas tube, the flash hider fitted just beyond the syock gas block/sight base.
He also prefered the 20 rounds mags for entry work (he is a professional with many years of experiance at this sort of thing).
He'd had thirty shot mags get in the way while slipping in through a window, almost gave away his position that time.
A high profile mass gang hit near here many years ago pointed out the possible problems of extended magazines. The shooter took out eight gang members who'd ambushed him and left him for dead earlier that day.
He used an M1 Carbine with thirty shot mag. The scene was a popular bar.
After killing his intended targets he was backing away when he somehow bumped the banna mag against the corner of the bar. He'd suffered buckshot wounds to the head several hours before so he probably was a bit rocky on his feet.
The magazine popped out and fell on the floor. This gave companions of those he'd killed the opportunity to jump him before he could reload. After the beat down he was dragged into the parking lot and a girlfriend of one of his victims ran back and forth over him with her car, about a dozen times.
Everyone involved was a total scumbag, so no tears shed for these culls.

[Eagles6]

http://accurateshooter.wordpress.com/2010/02/17/usmc-adopts-new-open-tip-sost-5-56-ammo/<p>
Thanks Starmetal.
To mike in co.
Obviously this has been an issue since Eugene Stoner developed the rifle using that round.
I don't think the Marines wanted a new, more effective bullet in 5.56 because it goes with their new boots.

[Eagles6]

http://www.marinecorpstimes.com/news/2010/02/marine_SOST_ammo_021510w/

[Lloyd Smale]

websters defintion of a carbine
1 : a short-barreled lightweight firearm originally used by cavalry
2 : a light short-barreled repeating rifle that is used as a supplementary military arm or for hunting in dense brush

theres no inch limit to what is considered a carbine. a 94win at 20 is a carbine. An win 86 at 22 is a called a carbine. Its just a generic term used to decribe a short handy gun. As for the military i was there and i never once heard any ar called a carbine there by anyone. They are all rifles to the military. if you want to call your 20 inch ar a carbine youd be just as right as the next guy calling it a rifle. As to gas lenght ive heard all the arguments about the longer being more reliable but ive got a few 16 inch guns and they run just as well as the 20 i have. I would sure think that if the short system wasnt reliable and 30 round mags werent reliable that the navy seals sure wouldnt use them! Thats the main grip i have with ars and the guys that shoot them. Everyone is an expert and theres lots of snob appeall to them. You will get guys that will tell you that you need a noveski (spelling) or some other 2-3000 dollar custom ar to get a reliable good shooting gun. That you need 300 dollar 4 rail forearms because the 100 dollar ones are junk. Bottom line is the main differnce between a 2000 dollar gun and a 1000 dollar gun is the better gun probably has a better bolt group. That may be fine for a gun thats going to be shot full auto but for the average guy its a waste of good money to buy a 2000 dollar ar. If your really conserned a 1000 dollar gun with a 200 dollar bolt will get you there. Sorry i guess im going way off topic now but the main point in my post is i get sick of all the know it alls. Internet experts that think they know it all but the closest theyve come to using an ar in combat is watching the military channel!!

[mike in co]

websters defintion of a carbine
1 : a short-barreled lightweight firearm originally used by cavalry
2 : a light short-barreled repeating rifle that is used as a supplementary military arm or for hunting in dense brush

theres no inch limit to what is considered a carbine. a 94win at 20 is a carbine. An win 86 at 22 is a called a carbine. Its just a generic term used to decribe a short handy gun. As for the military i was there and i never once heard any ar called a carbine there by anyone. They are all rifles to the military. if you want to call your 20 inch ar a carbine youd be just as right as the next guy calling it a rifle. As to gas lenght ive heard all the arguments about the longer being more reliable but ive got a few 16 inch guns and they run just as well as the 20 i have. I would sure think that if the short system wasnt reliable and 30 round mags werent reliable that the navy seals sure wouldnt use them! Thats the main grip i have with ars and the guys that shoot them. Everyone is an expert and theres lots of snob appeall to them. You will get guys that will tell you that you need a noveski (spelling) or some other 2-3000 dollar custom ar to get a reliable good shooting gun. That you need 300 dollar 4 rail forearms because the 100 dollar ones are junk. Bottom line is the main differnce between a 2000 dollar gun and a 1000 dollar gun is the better gun probably has a better bolt group. That may be fine for a gun thats going to be shot full auto but for the average guy its a waste of good money to buy a 2000 dollar ar. If your really conserned a 1000 dollar gun with a 200 dollar bolt will get you there. Sorry i guess im going way off topic now but the main point in my post is i get sick of all the know it alls. Internet experts that think they know it all but the closest theyve come to using an ar in combat is watching the military channel!!

dang you are good.........
i bought one ar in my life( my ar10t)..built all the rest..
no 4 rail gadgets
scopes and dots, yes.....
and while i was on submarines...we did qualify/familiries on small arms....45's( yes i pre date 9's), shotguns, m16's mk 48's, icmb's, cruise, etc...

mike in co

[lead-1]

According to the ATF, there IS no such thing as a Carbine.
It's Long gun, Pistol or Other.
Are you suggesting I call in a 4473 and say "carbine" when asked what type of firearm it is?
I already know what that'll tell me.
"that is not a valid answer. Please repeat firearm type"
An M16A2 is a rifle. M4 is a "carbine LENGTH" rifle.
Common vernacular aside, in my business, if the ATF says it's something, that's what it is. Regardless of what the common name for it is.

Not intending to stir the pot but I got this first hand last week when a friend ask me to call in a 4473 check. The party was purchasing a Bushmaster and when reading the info off to the nice lady on the other end I responded "rifle" when she asked firearm type. She politely informed me that "rifle" was not one of my choices it would have to be Long gun, Pistol or Other.
This debate could go on for years and a muzzle loader is a muzzle loader but my son's rifle has a 26 in. barrel and my friend's carbine has a 20 in. barrel.
Carbines are usually considered to be the shorter barrel firearms but I agree that there is really no set carbine length but the shorter of the particular family is usually called a carbine.

[klcarroll]

WHEW!!!!!!!!!

This discussion has come a long way from Firebricker's original question regarding the operational aspects of different barrel length/gas tube length combinations!!!

Firebricker's question is also the one that actually interested me. (I've heard enough about the BATF to last me THREE lifetimes!)

The gas port location relative to the chamber and the length of barrel "downstream" from the gas port will obviously have a direct effect on both the peak gas pressure presented to the bolt AND the duration of that pressure pulse: .....I would like to hear more discussion on that subject; ......Particularly combinations that give the most functional flexibility with mid-range or reduced loads for "non-tactical" applications.

Kent

[Storydude]

With reduced loads, the CAR length gas system will offer better performance in a sub-20" rifle.
With full loads, the CAR length system, in sub-20" barrels needs a heavier buffer to reduce impulse.

Not even going to mention the "pigtail" systems.