14.5" AR - Carbine vs Middy Upper

[Marcus99]

I'm wanting to put together another AR build real bad. This time I want to keep it as compact as possible (without getting into the NFA SBR realm). I'm wondering if a midlength or carbine gas system would be better suited to a 14.5" + permanent flash hider? I did some research and it seems peoples opinions are a 50/50 split.

On another note, does anyone have experience with an Eotech 512 and standard FSB? I know that without a riser the top of the front sight will be in the center of the dot, which I think is really convenient for a backup sight, but will it also be distracting?

 

[atmay]

Personally, I prefer a middy to carbine (on a 16" anyway, 14,5 won't be too different), especially if you're going for a gun with a standard FSB (longer sight radius).

As for perfect co-witness, it depends on your personal preference. I have my AimPoint set up for perfect cowitness , but most people I've seen with EoTechs use lower 1/3rd. My suggestion would be to buy just the sight now, and the riser later if you decide you need it.

 

[jasons]

The military designed the carbine gas system specifically to go with the 14.5" barrel. I'm sure they had a good reason.

 

[ColdDayInHell]

The military designed the carbine gas system specifically to go with the 14.5" barrel. I'm sure they had a good reason.

Yup. My DGW build will have a 14.5 , I can't wait. BCM makes excellent products.


Sent from my POS iPhone

 

[Supermoto]

The military designed the carbine gas system specifically to go with the 14.5" barrel. I'm sure they had a good reason.

Yep,
Dwell time.

If you are going to shoot low pressure ammo and Nato, I would go carbine. If just Nato, then midlength will be fine

 

[Alex9661]

The military designed the carbine gas system specifically to go with the 14.5" barrel.

Not exactly. It was designed for 10" barrels. Google R607, R608, and XM177.

 

[ChevyGuy91]

I have a carbine and like it just fine, although, if the mid 14.5's had been so common back when I got mine, I would have taken a long look at them.

I pinned a 14.5" barrel because I live in MA and would have pinned it anyways. If I lived in NH, I would probably look more into a midlength 16" so I can change out the muzzle device as I wanted to.

 

[NHKevin]

Go for the mid-length.

 

[MichaelJR]

General consensus is that 16"+ barrel for mid (I mean whole barrel, not w/ flash hider). Anything under, go carbine.

 

[ColdDayInHell]

General consensus is that 16"+ barrel for mid (I mean whole barrel, not w/ flash hider). Anything under, go carbine.

+1

DGW better be shipping our damn lowers soon.

 

[jasons]

Not exactly. It was designed for 10" barrels. Google R607, R608, and XM177.

I'm talking about widely adopted, proven designs, not experimental crap that didn't work properly without installing wacky muzzle devices.

http://www.examiner.com/article/car...s-systems-a-brief-history-of-the-ar15-carbine

The next carbines we will discuss are the R607 and R608. The R607 was a "standard" SMG analogue, while the R608 was intended as a "survival rifle" for USAF pilots and aircrew. For all intents and purposes of gas system and functionality, they were identical. Both featured a 10" barrel and 7" gas systems, and were originally fitted with either three prong or duckbill flash suppressors, or conical flash hiders. While the length of the gas system was nearly halved compared to the M16 and the R605, both still had marginal dwell time, with the barrel terminating almost exactly at the end of the FSB.

Again, the reliability of these two platforms was found to be initially unsatisfactory. In an attempt to improve dwell time, as well as to soften the rather sharp report of the 10" barrels, they were fitted with 3.5" moderators that served the dual function of incresing back-pressure, and reducing the sound signature of the extremely short barrel. While the R608 survival rifle was ultimately not adopted, the R607 was apparently satisfactory enough to warrant further development, however, the R607 was difficult and expensive to produce, owing to the complex telescoping stock mechanism and shortened handguards, both of which had to be manufactured from cut down full sized furniture.

Bottom line, the carbine gas system is going to be more reliable than a mid-length when used on a 14.5" barrel. There's a reason that there are 100's of thousands of M-4 carbines deployed with 7" gas systems.

 

[MichaelJR]

+1

DGW better be shipping our damn lowers soon.

I already have mine and yours. Shot them all. I'm keeping them all.

 

[Maxxum2012]

+1

DGW better be shipping our damn lowers soon.

I went the other direction for my DGW...building a beast! Arrives this week.

http://www.midwayusa.com/product/173618/dpms-ar-15-flat-top-upper-assembly-223-remington-1-in-8-twist-20-bull-barrel-stainless-steel-with-free-float-handguard

 

[ColdDayInHell]

I already have mine and yours. Shot them all. I'm keeping them all.

I went the other direction for my DGW...building a beast! Arrives this week.

http://www.midwayusa.com/product/48...rel-stainless-steel-with-free-float-handguard

Ah very nice. I don't hunt or pick off varmints, so a 20" wouldn't do much for me. Since I already have a 16" I decided to get the 14.5" BCM carbine. It'll be a beast as well.