M16/AR-15 rifles come in all types of configurations but they are based on two ideas. One basic form is the rifle with a 20" barrel and a fixed, standard, stock. The other basic form is as a "carbine" with a 14.5" (16" civilian) or shorter barrel and a collapsible stock. But regardless of the "carbine" moniker, the variations with collapsible stock are more submachineguns than rifles. A true carbine, based off the rifle design, was and is missing.

The utility of the M4 and similar folding stock designs is well known. It is a fantastic weapon. The folding stock makes it easier for parachuting, for carrying in helicopters and vehicles, and handier in buildings and tight places. But aside from accommodating small shooters, there is no shooting advantage to the folding stock and the tiny handguard.

The longer 20" barrel of the rifle version has the advantages of shooting cartridges to greater velocity. It also provides a longer sighting plane for iron sights. Most significantly, the longer handguard and fixed stock are better suited for accurate, carefully aimed shooting.

So, where is the true carbine? It would be similar to the rifle but with a shorter, more compact design. For example, the Winchester Model 94 was made in 24" and 26" barreled rifle versions and 20" and shorter barreled carbine versions. Other examples are the long military Mauser rifles and their artillery, cavalry, and engineer carbines.

When looking for an AR-15 carbine to use for general hunting all I could find were offerings with folding stocks. I have no plans to use my hunting carbine for parachuting or CQB and I prefer the shootability of a fixed stock and decent handguard. None of the folding stock ARs I could find were suitable. Instead, I decided I needed to configure a true AR-15 carbine.

I ordered a Rock River Arms upper with 16" barrel, mid-gas port, and mid-handguards. The barrel is 4 inches shorter than the standard M16 rifle barrel. Then, instead of connecting this upper to a lower with a folding stock, I used a standard rifle lower.

The result is more than satisfactory. It is 1/2 pound lighter and 4 inches shorter than the rifle and handles like a true carbine. There are a couple of additional benefits. Because both sling loops are on the bottom of the carbine I can affix a standard sling in the same manner as one would on the rifle. I never did like side-mounted triple-point slings. My carbine also balances better than either the rifle or a folding stock version. The full length rifle tends to be a little front heavy. The shorter barrel of my carbine corrects that. The folding stock versions also tend to be front heavy because they are lighter in the rear. Again, my carbine corrects that with the rifle stock. The result is better balance and handling.

Now, I know I didn't invent anything. Surely, many people have discovered what I have by putting a 16" upper on their standard rifle lower. But I am surprised that no company seems to be offering this configuration and, even more so, that the Army never adopted a true carbine like this.

A friend and I have been replace the adjustable stock on our carbines for years.

If one doesn't need the adjustable stock the fix stocked ones handle better point, better and for me get on target faster.

I think colt at one time offer something like this. They change the configuration of their models faster then one can say boo.

I prefer flat top upper and optics.

You have a mid length gas system, which was developed by Armalite/Eagle Arms. This is not the original 'CAR" or carbine version. Even though it uses the 16 inch barrel.
The reason the Army has the collapsible stock is for easy entry and egress from vehicles and buildings. Not because it makes a better shooter. Civilian shooters are always better served by the fixed stock.

dpcd - Yes, mid length and not the 11.5" or 14.5" barrelled CAR-15/M4s. That way the front sight and bayonet lug are in proper relation to the muzzle. I did not mean it should have been an either/or. The M4 has its place as does the 20" rifle. But a 16" carbine would also fill a need, I think this is especially true with all the attachments soldiers put on the rifle. Bringing it back 4" would improve handling and balance. I think it would be a useful option that, as I said, should have been.

Late US Mil (SPECOPS mainly) models of the AR have 18" bbls and mid length gas systems and real triggers ( Gieselle Automatics).

Folks who know what is needed make things that work- while the big Army and Marines stick with the M4, which is over gassed, under bbl'd and resultantly inferior in terms of internal, external and terminal ballistics, espc given the moderate diameter and KE of the caliber required.

I have long considered a mid weight free floated 20 inch bbl'd collapsible/adjustable buttstock equipped AR with a good or better quality trigger shooting 75 grn modern bullets at decent velocity ( I get 2850 fs from 75 Horn BTHPSand Varget) the cats meow for all things less than 800m tactically suitable. Now I just need a dual construction bullet for both penetration and fragmentation to be at optimum for the platform.

My next project is a stout 6mm at a nominal 2950-3000 fs from a 20 inch bbl.... The 6mm Hagar or the 240 Tomahawk fit the bill ( the tomahawk can seat a 105 Amax at 2.26"-mag length and leave a 20 inch bbl at 2800, 85s at 3150)- 6.8 SPC is parent case so 25 fit in a 556 30 round spec mag.

Being tied to NATO spec is a dead weight on modern US Arms and Ammunition development.

Sorry, doesn't look Gimmicky enough for today's soldiers.

Grizz

The mid gas port carbine could be just as easily built with rails for any sort of sights and lights.

The sad truth is that too many of today's soldiers can't shoot with reasonable accuracy regardless of how many accouterments are hanging on the rifle. That's been the case for decades.

The good truth is that anyone adept with the aperture and post sights of the M16 can use them to shoot acceptable hunting sized groups beyond 200 meters.

I went old school on this one because I don't want to carry 2 lbs of junk on the barrel that I can't, or won't, use while hunting.

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The good truth is that anyone adept with the aperture and post sights of the M16 can use them to shoot acceptable hunting sized groups beyond 200 meters.

If you can see a defined target and you have goods eyes.

Optics are very superior to peep and open sites in most hunting and tactual situations.

Just because too can shoot groups on the range doesn't mean you can tread that bullet through brush. Pick out that knee and place a round into it.

My favorite iteration is an 18-20" barrel (.750" gb) with a simple carbon fiber free-float tube (Clark Custom's are nice), rifle length gas, Ace Skeletal rifle stock. Handles great, doesn't frost your hands in cold weather and just feels good to me.

I have done something similar but with the "dissipator" upper which has the full length handguards and sight radius. It doesn't look very "tactical" so I guess I'm a nerd!

Looking back through the posts above I see that I failed to mention the caliber is 6.8 SPC. The rifle will be used to hunt with the iron sights. They are very robust, very quick, and never fog. In a pouring rain all that is needed is to blow a puff of air through the rear aperture to get the water out. I used to compete with M16s in Service Rifle matches and I know they can be accurate without optics. The added value of the 6.8 cartridge is that I can hunt deer and perhaps pigs with it. I might even try it on a black bear hunt.

But for now, I was wondering what sort of intrinsic accuracy the little rifle is capable of. An optical sight lets you see the target more clearly and you can place magnified crosshairs on a target with more precision than with a peep and post. So, I mounted a 3X Burris 332 on the rifle and shot some prone-supported 100 yard 5-shot groups. I was hoping to get a baseline of the optimal accuracy to work toward as I train myself to shoot this rifle with iron sights.

To my surprise and dismay the best I could do was just under 5". Perhaps, I pondered, the 6.8 cartridge isn't capable of the sort of accuracy I am used to with the 5.56. Or is it because of the chrome lined bore? Or is the build "sloppy"? I decided to sleep on the issue.

Yesterday, I removed the Burris optic and shot more 100 yard 5-shot groups with the issue sights and the same ammo from the day before. This time the groups were around 1-1/2"! For fun I fired ten rounds rapid fire and that went into 4". The rifle is a keeper for sure but I can only wonder why it shot worse with 3X optics.

To head off the most obvious question let me say that the 3X optic was mounted properly and I made sure it was locked down tight. The most obvious difference I noticed in shooting with and without the optics was that I had to keep my head up to use the glass. Maybe that was enough to put accuracy off.

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The most obvious difference I noticed in shooting with and without the optics was that I had to keep my head up to use the glass

That is the reason the invented flat top AR.s

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Originally posted by citori:
I have done something similar but with the "dissipator" upper which has the full length handguards and sight radius. It doesn't look very "tactical" so I guess I'm a nerd!

I've built a couple dissies ... i love them

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Originally posted by p dog shooter:

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The most obvious difference I noticed in shooting with and without the optics was that I had to keep my head up to use the glass

That is the reason the invented flat top AR.s

I know this, of course. If I was going to be using it with glass a flat top is what I would have. But I will be using this with the irons. That was my intent from the start and I am pleased with how well they do with peep and post. I just thought I would temporarily throw a scope on it because I was curious to see what accuracy it was capable of. I never imagined I'd be getting worse groups by doing that.

Attach a quality cantilever optic mount, add a dot sight of your choice..... Cheek weld is same as with irons, some mounts hold the dot just above the aperture, some adjust for height.

Both our receivers wear A1 riflestocks, no matter what upper we're playing with. This one is a high-mileage 11.5" - gas port is so badly eroded we'd need something like a 9mm or MGI buffer to control ROF were we using a collapsible.

Nice camera shot of the brass in the air! The place looks a little like Knob Creek but I'm probably mistaken.

2011 GMBSC, Eden, VT. Another illustration of the riflestock's practical advantage. They may not look as nice, but.........

Kid's here shooting an HK51 (7.62x51, 7" bbl). Surprisingly manageable with the riflestock, less so with the HK collapsible.

Brass in the air is always fun!