View Full Version : Colt 6940: Cut it down to 14.5, is it possible?
I understand the 6940 upper isnt easily modified due to the proprietary nut system or something along those lines.
Is it possible to cut down my factory barrel to 14.5 and have a different muzzle device pinned/welded on the end?
JBecker 72
10-18-13, 15:10
Call up Adco, I'm pretty sure they would be able to do it.
Just curious prez... Why do you want to cut 1.6" off of the barrel? GH
Just curious prez... Why do you want to cut 1.6" off of the barrel? GH
This. Do not cut a Colt barrel for that little distance.... Just buy a 6944 and sell the 6940...
Call up Adco, I'm pretty sure they would be able to do it.
This... I don't understand what people get so wrapped around the axel about cutting the Colt barrel, there is nothing overly special about them.
Except it will take away the value from that upper. You cannot change that barrel without special tools.
There is no real gain from 16" to 14.5" other than perception.
This... I don't understand what people get so wrapped around the axel about cutting the Colt barrel, there is nothing overly special about them.
Except it will take away the value from that upper. You cannot change that barrel without special tools.
There is no real gain from 16" to 14.5" other than perception.
Tacticool will be achieved however. D:cool:
This. Do not cut a Colt barrel for that little distance.... Just buy a 6944 and sell the 6940...
Is the only difference between the two barrel length?
I'm a little lost as to why someone would wish to do this unless... They have a bayonet and want to mount it without an adapter. That bayo lug is worthless as tits on a bore in the 16" barrel variety.
But that's all I can think of.
Is the only difference between the two barrel length?
Yes. The 6944 is factory 14.5 while the 6940 is factory 16". There is even a 6944 on GB right now, go get it!
Except it will take away the value from that upper. You cannot change that barrel without special tools.
There is no real gain from 16" to 14.5" other than perception.
This. And even with a tool it's a major pain in the ass!
Yes. The 6944 is factory 14.5 while the 6940 is factory 16". There is even a 6944 on GB right now, go get it!
Cool. There was only the 6940 when I got mine.
Except it will take away the value from that upper. You cannot change that barrel without special tools.
There is no real gain from 16" to 14.5" other than perception.
Special tools other than what's normally required for cutting a barrel?
ADCO can do it. Personally, I don't see why everyone gets all bent out of shape when it comes to cutting a Colt barrel. It's not anything particularly special, but if you are more concerned about resale value or holding on to a collectors item, then I guess I could see not wanting to molest it. Personally, if you're planning on using the gun and keeping it, I say modify it to fit your needs, or if possible and it makes more financial sense, sell it and buy something that fits your needs. In the case of the 6940, if you want a non-NFA Colt MRP, that's your gun. If it came in a 16" middy I wouldn't consider cutting it, but it doesn't and 14.5" has been proven to be the ideal length for a carbine length system, so I could see cutting it for those reasons. Ultimately, it's your gun to do with as you please, and the guys in this thread are not wrong when they say that cutting it will make it less desirable to others and hurt its resale value, so keep that in mind.
Special tools other than what's normally required for cutting a barrel?
It requires a proprietary barrel wrench to remove the barrel nut. You can buy one from Brownells I believe, or ADCO has one and can remove the barrel for you.
I say do it.
A pinned 14.5" is noticeably handier than a 16" + flash hider, not to mention the fact that they look better.
The only time a 16" carbine upper is easy to sell is during a panic. The rest of time, they're hard to move.
I disagree completely.
If you can't maneuver with an additional 1.5" or so inches of barrel, it's not the equipment that's a problem.
Looks should be irrelevant other than for Facebook pics.
One would argue (aside from the 6940) it is easier to sell a 16" and I suspect many here would agree. If you pin a 14.5" barrel, you are then limited as to what modifications you can make later. So you are limited to a rail that uses a standard barrel nut (for the most part) unless you are prepared to spend more have the device removed and any possible damage to said device.
I say do it.
A pinned 14.5" is noticeably handier than a 16" + flash hider, not to mention the fact that they look better.
The only time a 16" carbine upper is easy to sell is during a panic. The rest of time, they're hard to move.
I spoke to Ken Elmore about this many months ago and I am pretty sure that he told me the average person will not be able to remove it even with that particular wrench from Brownells.
I'm sure that ADCO can do it, but the juice isn't worth the squeeze.
It requires a proprietary barrel wrench to remove the barrel nut. You can buy one from Brownells I believe, or ADCO has one and can remove the barrel for you.
justin_247
10-19-13, 15:16
A pinned 14.5" barrel is about 3/4"-1" shorter than a 16" w/ an A2 flash hider.
It's amazing what people will pay to reduce their barrel length by 3/4"-1".
justin_247
10-19-13, 15:25
The difference between the two.
http://i293.photobucket.com/albums/mm49/PreludePowerR/IMAG0167.jpg
The difference between the two.
http://i293.photobucket.com/albums/mm49/PreludePowerR/IMAG0167.jpg
One of the single most informative pics I've seen on M4C.
I disagree completely.
If you can't maneuver with an additional 1.5" or so inches of barrel, it's not the equipment that's a problem.
Looks should be irrelevant other than for Facebook pics.
One would argue (aside from the 6940) it is easier to sell a 16" and I suspect many here would agree. If you pin a 14.5" barrel, you are then limited as to what modifications you can make later. So you are limited to a rail that uses a standard barrel nut (for the most part) unless you are prepared to spend more have the device removed and any possible damage to said device.
I hear you, and maybe this is what you meant about the 6940, but you're stuck with the rail anyway. It is a very particular gun and definitely not for everyone with the short MRP rail. It would make a nice SBR in my opinion. I might cut mine down if I ever shell out for a tax stamp.
I spoke to Ken Elmore about this many months ago and I am pretty sure that he told me the average person will not be able to remove it even with that particular wrench from Brownells.
I'm sure that ADCO can do it, but the juice isn't worth the squeeze.
I believe that. The tool I got from Brownells didn't even fit into the nut on my gun. Might have been user error, but either way I gave up and returned it. I needed it removed to get my upper coated though.
A pinned 14.5" barrel is about 3/4"-1" shorter than a 16" w/ an A2 flash hider.
It's amazing what people will pay to reduce their barrel length by 3/4"-1".
Your picture isn't really comparing apples to apples with different muzzle devices. Furthermore, as I mentioned before, you are still reducing the barrel length by at least 1.5", sometimes more if you are pinning a longer muzzle device and your smith cuts to achieve an overall length of 16.1". That, in my opinion, is the only real benefit of cutting a 16" carbine system, to make a little softer shooting and more reliable overall weapon. This is assuming you can't or don't want to sell the upper and buy a gun off the shelf configured like you want.
How about doing it to optimize gas pressures to improve recoil impulse and reduce bolt wear and tear and gas port erosion, etc. In other words to return the gun to its proper function envelope via a vis gas pressure profile, dwell time, etc. Or would just going with a heavier buffer achieve the same thing. I guess the anti carbine gas + 16" bbl nazis have planted a bug in my bonnet that won't shut up.
justin_247
10-19-13, 17:33
Your picture isn't really comparing apples to apples with different muzzle devices. Furthermore, as I mentioned before, you are still reducing the barrel length by at least 1.5", sometimes more if you are pinning a longer muzzle device and your smith cuts to achieve an overall length of 16.1". That, in my opinion, is the only real benefit of cutting a 16" carbine system, to make a little softer shooting and more reliable overall weapon. This is assuming you can't or don't want to sell the upper and buy a gun off the shelf configured like you want.
This makes absolutely NO logical sense.
First of all, you can't use the same muzzle device as you would use on a 16.1" barrel. You *must* use a muzzle device that adds at least 1.6" to the length of the muzzle after it has been permanently attached. As a result, when people choose muzzle devices, they choose only ones that add just the right amount, and no more. If they didn't, there is no sense in cutting down the barrel to only 14.5" in the first place - they would cut it down further.
But since you're so hung up on the muzzle device, here's two pics using the same brand of muzzle device, taken from this thread (https://www.m4carbine.net/showthread.php?t=106651):
http://i609.photobucket.com/albums/tt176/jbarbaresi/Guns/IMG_1026.jpg
http://i609.photobucket.com/albums/tt176/jbarbaresi/Guns/IMG_1027.jpg
http://i609.photobucket.com/albums/tt176/jbarbaresi/Guns/IMG_1029.jpg
I will re-emphasize this again:
Cutting down your barrel to 14.5" and then permanently affixing a muzzle device designed to bring the overall length to over 16" DOES NOT reduce the overall length by 1.5".
Oh, and I forgot to add. With regards to the overall reliability of the weapon, which muzzle device you choose can actually impact that. Battlecomps, for example, can increase the overall pressure at the gas port. There is a member of this forum who could not get his SBR'd Bushmaster barrel to cycle properly, but once he added the Battlecomp, it cycled just fine.
So, if your intent is to somehow "increase reliability" (I'm literally LOL'ing right now) by cutting down a 16" barrel to 14.5", you better take the muzzle device into consideration (which you do not).
JBecker 72
10-19-13, 17:47
I recently had a Colt 14.5" barrel with a BE Meyers flash hider installed on one of my rifles. It saved me 7/10" over a 16.1" barrel with an A2. I'll be the first to admit the only reason I did it is because I prefer the looks of the 14.5" on a M4 barrel.
As others have said, it doesn't make that much of a difference. But if you want to, go for it. I have a 16 and a 14.5, they are both fun. It shouldn't be a problem for a gun smith to do the work with the barrel on the receiver. I had a savage bolt action cut and re-crowned and the guy left the rifle assembled.
There is a case for this - if the OP is moving to a state where a permanent muzzle brake is required anyway, and wants to take the opportunity to spend a fair bit of cash shortening the rifle by 1.3" or so it's hardly a step backwards - just a slightly inefficient way of getting an almost-SBR.
This makes absolutely NO logical sense.
Sorry, I'm afraid you misunderstood me or perhaps I worded my post poorly.
First of all, you can't use the same muzzle device as you would use on a 16.1" barrel. You *must* use a muzzle device that adds at least 1.6" to the length of the muzzle after it has been permanently attached. As a result, when people choose muzzle devices, they choose only ones that add just the right amount, and no more. If they didn't, there is no sense in cutting down the barrel to only 14.5" in the first place - they would cut it down further.
Sure you can, but you are assuming I said to just cut to 14.5" arbitrarily, which I did not. I realize you were talking about a 14.5" barrel in the post I quoted, so perhaps that's where we got mixed up. I said pick a muzzle device and then cut your barrel to achieve a total overall length of 16.1". This means if you are using an A2 flash hider, you will cut less barrel than if you are using, say, a Smith Vortex.
But since you're so hung up on the muzzle device, here's two pics using the same brand of muzzle device, taken from this thread (https://www.m4carbine.net/showthread.php?t=106651):
http://i609.photobucket.com/albums/tt176/jbarbaresi/Guns/IMG_1026.jpg
http://i609.photobucket.com/albums/tt176/jbarbaresi/Guns/IMG_1027.jpg
http://i609.photobucket.com/albums/tt176/jbarbaresi/Guns/IMG_1029.jpg
Not that it matters, but again, those are not the same muzzle devices...but it does illustrate the point I was trying to make, and I was never trying to dispute anyone on this...you just assumed I was. Overall length is not reduced by 1.5" but barrel length (from a closed bolt to the end of the threads, where the gases begin to exit the barrel) can be, depending once again on which muzzle device you use.
I will re-emphasize this again:
Cutting down your barrel to 14.5" and then permanently affixing a muzzle device designed to bring the overall length to over 16" DOES NOT reduce the overall length by 1.5".
I will re-emphasize this again. I never said that it would.
Oh, and I forgot to add. With regards to the overall reliability of the weapon, which muzzle device you choose can actually impact that. Battlecomps, for example, can increase the overall pressure at the gas port. There is a member of this forum who could not get his SBR'd Bushmaster barrel to cycle properly, but once he added the Battlecomp, it cycled just fine.
So, if your intent is to somehow "increase reliability" (I'm literally LOL'ing right now) by cutting down a 16" barrel to 14.5", you better take the muzzle device into consideration (which you do not).
Laugh all you want, but more than one person on this forum who knows what they are talking about has said that a 14.5" barrel or less is an ideal length for a carbine length gas system, and is the length the M4 was actually designed for. Maybe it doesn't make a big difference, but then why are there so many proponents of a 16" middy?
I have not seen any data regarding muzzle devices and their impact on gas pressures, but I don't doubt that there would be some correlation depending on the design.
justin_247
10-19-13, 21:01
Laugh all you want, but more than one person on this forum who knows what they are talking about has said that a 14.5" barrel or less is an ideal length for a carbine length gas system, and is the length the M4 was actually designed for. Maybe it doesn't make a big difference, but then why are there so many proponents of a 16" middy?
There's a whole other thread about this, dude. There is a big difference between "less ideal" and "less reliable." I have yet to see anybody state that a properly built carbine with a 16" barrel is "less reliable." In addition to saying that, I have yet to see anybody post any statistical data indicating as such.
I would go back and reread what has been written, because I think you've misread it.
There's a whole other thread about this, dude. There is a big difference between "less ideal" and "less reliable." I have yet to see anybody state that a properly built carbine with a 16" barrel is "less reliable." In addition to saying that, I have yet to see anybody post any statistical data indicating as such.
I would go back and reread what has been written, because I think you've misread it.
My fault, I realize I wasn't very specific with regards to reliability and gas system because, as you said, that is a whole other can of worms. The general consensus as I understand it is that the higher gas pressures of a 16" carbine system can cause some increased wear and tear on the reciprocating parts of the gun, and can require a heavier buffer and stronger extractor springs to operate more reliably. I am sure this is part of what you consider a properly built carbine, as would most people here. A 14.5" carbine or 16" middy operate at a lower pressure, which can make the gun a little more forgiving and not as hard on parts. I realize the 16" carbine is probably the overwhelming majority of setups out there, and over time people have learned what needs to be done to make it more reliable. I also doubt I or anyone else would notice a difference unless they were shooting thousands of rounds a year.
Generalpie
10-19-13, 22:25
I recently (9-10 months ago) was removed of my option to use a personally owned carbine. As such I was switched from a 14.5 with a phantom to a 16" 6920.
Subjectively I liked the 14.5 better but in practice I have noticed zero difference.
This is in deploying from inside a vehicle (crown vic), from the trunk and on several building searches, both training and operational as well as several wilderness training sessions.
If it makes you happy go for it. Personally unless I could go 12.5 or shorter I wouldn't be that is me. Your dime, have at it.
Joe
Not sure where this is all coming from but I will add this.
1. Colt 14.5" and 16" carbines use the same port size.
2. Colt 14.5" military weapons ship with H2 buffers and civilian 16" ship with H buffers.
3. They are for all intents and purposes the same weapon. I doubt very seriously that the slight difference in barrel length past the gas block has any significant impact on function at all.
4. Both weapons also use the exact same extractor assembly. I fail to see why you would need to do anything to an out of the box gun built correctly.
My fault, I realize I wasn't very specific with regards to reliability and gas system because, as you said, that is a whole other can of worms. The general consensus as I understand it is that the higher gas pressures of a 16" carbine system can cause some increased wear and tear on the reciprocating parts of the gun, and can require a heavier buffer and stronger extractor springs to operate more reliably. I am sure this is part of what you consider a properly built carbine, as would most people here. A 14.5" carbine or 16" middy operate at a lower pressure, which can make the gun a little more forgiving and not as hard on parts. I realize the 16" carbine is probably the overwhelming majority of setups out there, and over time people have learned what needs to be done to make it more reliable. I also doubt I or anyone else would notice a difference unless they were shooting thousands of rounds a year.
Your picture isn't really comparing apples to apples with different muzzle devices. Furthermore, as I mentioned before, you are still reducing the barrel length by at least 1.5", sometimes more if you are pinning a longer muzzle device and your smith cuts to achieve an overall length of 16.1". That, in my opinion, is the only real benefit of cutting a 16" carbine system, to make a little softer shooting and more reliable overall weapon. This is assuming you can't or don't want to sell the upper and buy a gun off the shelf configured like you want.
If you really think it makes a difference, I can show you a 14.5" with an A2 and a 16" with literally the same A2. But it won't, you'll see a rifle that's about 15.9" barrel length (it's on a SBR lower) and a rifle that's about 17.1" barrel length.
After having a pinned 14.5", an unpinned 14.5" upper, a 10.5" upper, and numerous 16" uppers, I can say with some authority that barrel profile, rail/handguard, muzzle device, accessories, buffer/receiver extension, and optics make vastly bigger differences in how your rifle handles than less than one inch of over all length difference and the weight of 1.5" of 4150 steel pipe.
Plus, 16" is cheaper (no paying for pinning necessary), lets you change muzzle device with ease, and you get a little better muzzle velocity.
Basically, 14.5" is only worth it IMO if you're making a clone for collection purposes or you're using the upper as a suppressor host. But in the latter case, I'd run 14.5" mid-length rather than carbine length. Also, I guess, if you live in a state where your muzzle device must be pinned and welded regardless of length, 14.5" is probably worth it.
Gents,
For comparison, a 6940 and 6944:
http://imageshack.us/a/img163/8140/vqaz.jpg
A 6944 barrel with pinned SAW flash suppressor:
http://imageshack.us/a/img203/3685/gclx.jpg
Call up Adco, I'm pretty sure they would be able to do it.
Called them, they can do it with quick turn around time. I'm considering it.
This. Do not cut a Colt barrel for that little distance.... Just buy a 6944 and sell the 6940...
The 6944 listed on GB currently is listed as SBR... is that accurate?
Tacticool will be achieved however. D:cool:
:dance3:
One of the single most informative pics I've seen on M4C.
I agree, i've searched around (not well enough I suppose) and thats the first time i've seen such a comparison.
I live in MD, we recently decided it would be in our resident's best interest to ban all these ugly weapons of war :rolleyes: so I cant buy that 6944. I'd like to find an upper, but not sure its worth the money someone would charge for one.
I've started liking longer hand rails on my rifles so this stock setup really doesn't allow me to run the gun as I would my others so I figured i'd fiddle with this just for kicks. I realize that the length I would be shaving off the front end wouldnt transform me into some mythical shooting God.
Im also the guy thats planning to chop off the base of my Springfield Professional to weld on a Stan Chen magwell so re-sale value means nothing to me as I have no plans to sell any of whats in my safe.
This thread has been very informative overall and I appreciate hearing the different view points of all.
The 6944 listed on GB currently is listed as SBR... is that accurate?
Yes.
However, the seller can permanently attach an extended flash suppressor, and the rifle would no longer be considered a SBR. The 6944 pictured in my preceding post has a pinned extended flash suppressor and is not a SBR.
rapomstage3
10-20-13, 18:08
I personally think 14.5" is perfect but if resale is an issue then I wouldn't do it. But if your going to keep it than wtf! I don't care what anyone says 14.5 looks damn short compared to 16" inches. Plus you can have it cut to 14.7 and use normal sized muzzle devices.
What is so difficult about buying a 6944?
Permanently attached flash hiders are garbage. They cause more money in the long gun than just getting an SBR.
In my opinion your money is better spent on ammo. If you really want a 14.5, however, it would be cheaper and easier to just send the upper to Adco and have them take care of it.
You would most likely loose money trying to sell your upper/gun to get a 6944 which is basically what you already have, and a sbr is an automatic $200 plus the cost of getting the barrel chopped. I think an sbr makes more sense with an upper that you can change handguards on anyway...
rbabbitt767
10-21-13, 00:22
ADCO can do it.
http://i.imgur.com/7w4FBr0.jpg?1
ADCO can do it.
http://i.imgur.com/7w4FBr0.jpg?1
Which Surefire brake is that? How do you like it?
What is so difficult about buying a 6944?
When HQMC makes you move every couple of years (to a state or country not necessarily of your choosing), owning a SBR looks to be a challenge. It is my understanding that SAW developed their 6944SE (permanently installed flash suppressor) as a rifle that could be configured to be California compliant.
Permanently attached flash hiders are garbage.
Yep.
They cause more money in the long gun than just getting an SBR.
If you you're inclined to change the flash suppressor, FSB, or rail then I agree the SBR would be cheaper in the long run. If you can't change the rail (Colt 6940 series) and are happy with the FSB and flash suppressor, then the cost for the 6944 and stamp is about the same as the rifle with the permanently installed flash suppressor.
In my opinion your money is better spent on ammo....
At $400-$500 over the cost of a 6940, it's tough to make an economic argument for the 6944.
rbabbitt767
10-21-13, 22:24
Which Surefire brake is that? How do you like it?
It's the AAC 51t Muzzle Brake. It's loud and obnoxious, but it mitigates a lot of recoil and it mounts the suppressor. I like them well enough.
Mall_Ninja
10-22-13, 00:03
With one of mine, the barrel needed to be cut anyways. So we cut it so that with the pinned YHM QD hider it would be 16" total. In my case not only did the barrel need to be cut, but the objective was to have the absolute shortest overall length (non-NFA) possible. So the barrel was just one part of the "package" so to speak. If someone was to change nothing else but cut an 1" or so then I would say you are crazy...
There is no real gain from 16" to 14.5" other than perception.
Yes,but I love perception:D Pete
http://www.fototime.com/6C3DC4123AC0320/large.jpg
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