14.5" Mid-Length Problems?

MWL556

MWL556

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Still fairly new to AR's but felt ambitious enough to jump into my first AR build last week, and have a barrel question that I have seen discussed on other forums, but not here...

My decision was to go with a 14.5" (pinned and welded), and I found a pretty good deal on one that I might buy - but it's a mid length, and the feedback I have been reading elsewhere is that they can been problematic if not built carefully, and won't run well with cheaper ammo - i.e. short stroking (insert Peter Griffin laugh) and related problems.

Like I said, this is my first build so I'm not banking on hitting one out of the park or building anything super fancy, but just looking for a fun, reliable AR in the end. As for ammo, I tend to shoot whatever I can get my hands on these days [sad2] (although it's looking brighter)... Any advice on this? Input on gas tube/block set-up and BCG choice? Should I just steer clear of this middie and wait until I've been around the block with a few different builds? I'm still considering a 16" too..

Much thanks for the help!
 
Save the headache and just go with a 16. Way more choices in barrels and no grief. I just don't understand the attraction to 14.5 barrels unless you are going to SBR it.
 
I have a 14.5" light weight mid length from Spikes that I scored cheap. I pinned a BCM comp on it, and it is a very flat shooter, I love it.

As long as the gas port is in spec and the buffer weight is matched, you won't have any problems.

IMG_3262_zps10ad14bf.jpg
 
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edmorseiii said:
I have a 14.5" light weight mid length from Spikes that I scored cheap. I pinned a BCM comp on it, and it is a very flat shooter, I love it.

As long as the gas port is in spec and the buffer weight is matched, you won't have any problems.
Click to expand...

Ed are you using the standard carbine buffer are one of the heavy versions?
 
My Daniel Defense lw 1:7 mid length 14.5 is a nice soft shooter and has so far eaten everything I've fed it without a single hiccup from steel cased 55 grain junk to 62 grain xm855. Running a standard carbine buffer and a battlecomp.
 
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Currently building a 14.5" Green Mountain barrel on a Detroit Arms Group lower with FDE Magpul goodies. It should be awesome, can't wait. 14.5" ARs have their niche, just like 20" heavy barrel builds. To each his own and **** the haters.
 
my carbine length and my mid length both have 14.5" barrels, afaik it really doesn't matter what the length of the barrel is as far as reliability is concerned, its really more the length of the gas system. my BCM mid length runs a lot smoother than my carbine due to the longer gas system, i like it and have had no problems.

 
Built two 14.5 mid-lengths, one with a Green Mountain Barrel the other BCM. Used a heavy buffer no issues, they shoot great.
 
Hardwired said:
Ed are you using the standard carbine buffer are one of the heavy versions?
Click to expand...

I have an H buffer in that carbine. A standard CAR buffer would probably have been fine, but the H is what I had in my parts bin, so that is what went in. After shooting it a bunch of XM855 I am happy with it so it is staying as it is.
 
ColdDayInHell said:
Currently building a 14.5" Green Mountain barrel on a Detroit Arms Group lower with FDE Magpul goodies. It should be awesome, can't wait. 14.5" ARs have their niche, just like 20" heavy barrel builds. To each his own and **** the haters.
Click to expand...

The one you bought though has a carbine gas system. I think the OP is talking about 14.5" barrels with midlength gas systems.
 
AllaSnackbah said:
my carbine length and my mid length both have 14.5" barrels, afaik it really doesn't matter what the length of the barrel is as far as reliability is concerned, its really more the length of the gas system. my BCM mid length runs a lot smoother than my carbine due to the longer gas system, i like it and have had no problems.
Click to expand...

The relevant length is the length of the barrel in front of the gas port.

Different-lengths.jpg

This shows a 20" barrel with a rifle length gas system
A 16" with a mid-length
A 14.5" with a carbine length

Notice how the length of the barrel in front of the gas port is almost exactly the same on all.

Too long of a barrel section in front of the gas port may result in a over gassed system
Too short of a barrel section in front of the gas port may result in a under gassed system
From what I understand, 18+ you want rifle length, 14.5-18 should be mid length, 10.5-14.5 for carbine(12.5 minimum seems to be more reliable) there is also a shorter pistol length system available for 10.5 and less barrels

A mix-matched example is a 16" barrel with a carbine gas system
This is when manufactures mess with the gas port sizes to make them run, and a combination of parts can result in a problematic gun

Don't get me wrong, a properly made 16" carbine barrel with bolt carrier and buffer of the proper weight will run fine. But that same barrel in a mid-length will cycle smoother and be softer shooting


To the OP's question: If the 14.5" mid length you want is from a reputable manufacturer, I'd say go for it. If its a lower end made barrel, I'd recommend saving your pennies for a better quality product to avoid trouble later
 
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Mid-Length is they way to go with a 14.5 or 16" barrel. they are much smoother shooters, and most of that Mid-Length problems BS you see is really old, and most of it is just pure crap.
 
SJan said:
The relevant length is the length of the barrel in front of the gas port.

View attachment 87273

This shows a 20" barrel with a rifle length gas system
A 16" with a mid-length
A 14.5" with a carbine length

Notice how the length of the barrel in front of the gas port is almost exactly the same on all.

Too long of a barrel section in front of the gas port may result in a over gassed system
Too short of a barrel section in front of the gas port may result in a under gassed system
From what I understand, 18+ you want rifle length, 14.5-18 should be mid length, 10.5-14.5 for carbine(12.5 minimum seems to be more reliable) there is also a shorter pistol length system available for 10.5 and less barrels

A mix-matched example is a 16" barrel with a carbine gas system
This is when manufactures mess with the gas port sizes to make them run, and a combination of parts can result in a problematic gun

Don't get me wrong, a properly made 16" carbine barrel with bolt carrier and buffer of the proper weight will run fine. But that same barrel in a mid-length will cycle smoother and be softer shooting


To the OP's question: If the 14.5" mid length you want is from a reputable manufacturer, I'd say go for it. If its a lower end made barrel, I'd recommend saving your pennies for a better quality product to avoid trouble later
Click to expand...

good post i didn't know all of that. rep'd
 
Carbine length gas is the optimum dwell time for 14.5, midlength for 16". Buy a good barrel from a good manufacturer with either length and it will run well. Gas Port size is going to be more important to getting the gun to run correctly and smoothly then port location. A lot of lower end manufacturer will over size the gas port, thinking in will increase reliability. It does not.
A 14.5" midlength is generally softer to shoot than a carbine. A 16 middy is definitely softer than a carbine.
 
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I'm a huge fan of mid length gas on a 14.5-16". I have owned both carbine length counterparts and I find the mid length variants equally reliable and significantly softer shooting. I run a normal buffer but many have had good success with H and H2 buffers. If you are building a competition gun you may want the carbine length gas if you run a comp and lightened BCG for a faster cycling time but I probably would not do that for a gp rifle.

IIRC the reason car length gas system on the M4 was to make room for the 203.
 
Glad to hear some positive feedback from those running mid-length 14.5" barrels.

The one I'm eyeballing is from Spikes, and their reputation seems to be pretty sound across the board. I'll be pinning/welding a Dynacomp Extreme on there as well for continuity... Even if I have to tinker with some different buffers or springs, it will be a good learning experience.
 
Cold Absolute Zero said:
. If you are building a competition gun you may want the carbine length gas if you run a comp and lightened BCG for a faster cycling time but I probably would not do that for a gp rifle.
.
Click to expand...

Actually, just the opposite. On a competition gun you would want the longest gas system possible. Carbine length systems will tear up a lightened carrier.
 
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MWL556 said:
Glad to hear some positive feedback from those running mid-length 14.5" barrels.

The one I'm eyeballing is from Spikes, and their reputation seems to be pretty sound across the board. I'll be pinning/welding a Dynacomp Extreme on there as well for continuity... Even if I have to tinker with some different buffers or springs, it will be a good learning experience.
Click to expand...

I just finished my build with a spikes 14.5 CHF mid length barrel with a battlecomp 1.5 that I welded on. I went with a st-t2 buffer and colt buffer spring.
9u5u5uma.jpg
 
Supermoto said:
Carbine length gas is the optimum dwell time for 14.5, midlength for 16". Buy a good barrel from a good manufacturer with either length and it will run well. Gas Port size is going to be more important to getting the gun to run correctly and smoothly then port location. A lot of lower end manufacturer will over size the gas port, thinking in will increase reliability. It does not.
A 14.5" midlength is generally softer to shoot than a carbine. A 16 middy is definitely softer than a carbine.
Click to expand...

I'm glad someone explained dwell time.

I like my guns to have just the right amount of gas. So I typically drill out the port just one size numerical bit then use a JP adjustable gas block. Then I can open it up a bit for break-in and back it way down once everything has worked in. I know its not the simplest way to do things, but it removes all the frustration when you have the ability to control the gas and therefore bcg speed. On toy guns that will be cleaned regularly I'll use a lower power spring with a standard weight buffer. On guns that I want to run when dirty, I'll use an extra power spring with an H buffer of some kind.

Don
 
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Supermoto said:
Actually, just the opposite. On a competition gun you would want the longest gas system possible. Carbine length systems will tear up a lightened carrier.
Click to expand...

Its my understanding that if you are going to use JPs lightened carrier, you should use their entire low mass operating system, including the adjustable gas block. So you could control that.

Are you using the lightened carrier with a standard block?
 
i've got a Rainier Arms 14.5" barrel on a Matrix upper and lower. I'm using a rifle length buffer though. I had some issues in the beginning with my gas tube, but that's because I didn't loc tite my gas black like i was supposed to (it moved). No more issues here.
My range only goes out to 200 yards and I shoot mostly steel ammo and this is a pretty good shooter at that range with that ammo.
 
dcmdon said:
Its my understanding that if you are going to use JPs lightened carrier, you should use their entire low mass operating system, including the adjustable gas block. So you could control that.

Are you using the lightened carrier with a standard block?
Click to expand...

I don't, i know many do without issue. There really is no downside to an adjustable gas block, the only issues I have had was on an extremely over gassed 14.5 carbine (.095 instead of .063 port) when I tried to reduce the gas by shutting down the block, it eroded a hole in the gas block

I'm running a custom cut bcg, jp lightweight spring and buffer with a adjustable gas block, 18" barrel rifle gas. I just ordered a taccom ultra low mass buffer and spring. Looking forward to trying it. Basically right now I can rip 50y A zone splits with very little muzzle movement in any direction, but I can feel a second impulse from the carrier that I would like to try reduce.
 
my BCM 14.5" midlength lightweight works very well, no feeding problems with any of the ammo I've tried (Prvi M193, Winchester M855, Tula steel case .223 -- just wanted to know if it would eat crap and run, and it did). Using a carbine buffer. BCM Mod1 perm attached. It's a real nice shooter.
 

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