Anyone?

Or should I just buy a colt 6520 and have it cut back?

M4 cut? Or M4 feed ramps?

At this time I do not know of ANY 14.5" lightweight 1/7 chrome lined barrels. Colt has made some in the past, however. These are quite rare.

Options are:
An LMT or BFI M4 barrel, turned down and using either a .750 fsb or a correct .625 fsb.
A cut down 6520 barrel.

Quoted: M4 cut? Or M4 feed ramps? At this time I do not know of ANY 14.5" lightweight 1/7 chrome lined barrels. Colt has made some in the past, however. These are quite rare. Options are: An LMT or BFI M4 barrel, turned down and using either a .750 fsb or a correct .625 fsb. A cut down 6520 barrel.

Long story short, I need to get a 6520 barrel and have it cut, huh?

Seems like spending the money to have a LMT barrel turned down would get ridiculously expensive, no?

The real cost of having the LMT barrel turned would be the new front sight base. You could skip that if you wanted, but why? An M16A1 front sight base from a parts bin at a gun show would do.

I had a barrel turned down and shortened by two inches, then threaded for $60. That wasn't bad at all.

My complaints about the 6520 would be 1) the lack of the slight bell at the muzzle in the barrel profile (not a real issue though, because you are going to pin and weld the FS anyway) and 2) the fact that half of the markings would be turned off. With the LMT at least you'd not have any markings.

So if it were me I would start with an LMT. LMT barrels are probably less expensive than Colt, and the LMT will require turning down, but the OAL and threads won't need to be touched. You'll also have to have the FSB (if you get a new one) attached. The Colt will require an OAL change and new threads. Same amount of machining.

I wonder exactly how much weight savings there is between an M4 and a lightweight (assuming both are 14.5")??

Quoted: I wonder exactly how much weight savings there is between an M4 and a lightweight (assuming both are 14.5")??

I do not know about the weight difference with the 14.5" barrel lengths.  The below weights are for the 16" barrels.  Possibly the weight difference is the same between the 14.5" barrels too.

16" Super Light Weight (A1 type) is 23.4 ounces.
16" M4 is 28.2 ounces.

You may not want to do this but if you have a m4 feed ramped upper to look at and compare, you can make m4 ramps in a regular barrel extension with a dremmel tool.  It isn’t hard at all.  You can take any old barrel and make m4 ramps in it.  It does however remove the parkerizing from the ramps but doesn’t hurt a thing.  Just an option..

They show up on the boards for sale once in a while. I picked one up a few months ago, 14.5" thin barrel, m4 ramps, marked "colt cmp 1/7". They are no made anymore, but for some time Colt carried a pencil barrel 14.5" A2 carbine.

Lightweight LMT M4 barrel on EE

Randall

Isn't Denny's recon barrel similar to what you are talking about?  I thought it was a weight reduced M4 profile but I might be wrong.

Quoted: Lightweight LMT M4 barrel on EE Randall

Here is the picture from your ad on the EE -



Where are the pins that are supposed to hold the FSB on? Just curious

Quoted: Quoted: Lightweight LMT M4 barrel on EE Randall Here is the picture from your ad on the EE - www.ar15barrels.com/gfx/lmt14lw.jpg Where are the pins that are supposed to hold the FSB on? Just curious

And is that phantom a 5C2, or is it a 28?

Quoted: Where are the pins that are supposed to hold the FSB on? Just curious

That's a mockup picture.
The pins were on my workbench.
Nobody asked where the barrel nut was either...
Now it's all put together properly.

Someone else asked about the phantom.
It's just a YHM 28, not a 28-5C2.

Randall

Quoted: At this time I do not know of ANY 14.5" lightweight 1/7 chrome lined barrels. Colt has made some in the past, however. These are quite rare.

We seem to have a handful of these barrels (Colts in chrome m4 14.5" configuration) out in the warehouse. $325 the each.

Veronica at M&A Parts

Quoted: Quoted: We seem to have a handful of these barrels (Colts in chrome m4 14.5" configuration) out in the warehouse. $325 the each. Veronica at M&A Parts

Then add about $50 for a permanent attached phantom and you are all set.
Either the Colt or the LMT would be a good barrel.

Randall

Maybe you could get a 14.5" CMMG Mod4 barrel and have it turned down to the appropriate thickness.  It's a 1/7, chrome lined, 4150 steel.  Just another thought for you.  MJD

Quoted: Maybe you could get a 14.5" CMMG Mod4 barrel and have it turned down to the appropriate thickness.  It's a 1/7, chrome lined, 4150 steel.  Just another thought for you.  MJD

It all depends on the price.
Going to cost at least $100 to re-profile, permanent attach a muzzle device and re-parkerize the whole thing.
Probably more like $125 to $130

Randall

Quoted: Quoted: Where are the pins that are supposed to hold the FSB on? Just curious That's a mockup picture. The pins were on my workbench. Nobody asked where the barrel nut was either... Now it's all put together properly. Someone else asked about the phantom. It's just a YHM 28, not a 28-5C2. Randall

Ah, re you permanently attached the FH after having it re-parked then. OK - was just being nosy. That's why I asked here and not on your ad. Thanks

Quoted: Ah, re you permanently attached the FH after having it re-parked then. OK - was just being nosy. That's why I asked here and not on your ad. Thanks

Oh no, I screwed myself really good on this barrel.
I tore down a complete LMT upper, pulled the FSB and barrel nut for profiling.
Then I slid the FSB on and perm attached the phantom.
Sent it off to park, the FIRST time...

It came back, I took the picture and realized the missing barrel nut.
Much cussing follows this discovery.
Take the phantom back off, put the damn nut on there and did it all AGAIN.
I don't ever want to take this barrel apart again!

Randall

Stag Arms just released there special addition 14.5" w/ phantom flashhider = 16.1, M4 cut upper, my cut barrel ext., made of 4150, 1/7 twist chrome lined, F-marked front sight

Quoted: Stag Arms just released there special addition 14.5" w/ phantom flashhider = 16.1, M4 cut upper, my cut barrel ext., made of 4150, 1/7 twist chrome lined, F-marked front sight

But, that's an M4 profiled barrel with the M4 cut in front of the FSB right?
If so, it does not fulfill the original request of this post which is a lightweight chrome lined barrel with m4 feedramps.

You would still have to re-profile and re-parkerize to end up with what the original poster wanted...

Randall

Quoted: Quoted: Ah, re you permanently attached the FH after having it re-parked then. OK - was just being nosy. That's why I asked here and not on your ad. Thanks Oh no, I screwed myself really good on this barrel. I tore down a complete LMT upper, pulled the FSB and barrel nut for profiling. Then I slid the FSB on and perm attached the phantom. Sent it off to park, the FIRST time... It came back, I took the picture and realized the missing barrel nut. Much cussing follows this discovery. Take the phantom back off, put the damn nut on there and did it all AGAIN. I don't ever want to take this barrel apart again! Randall

Wow - sounds like this project started off like shit and just went down hill from there. I feel for ya

Quoted: Wow - sounds like this project started off like shit and just went down hill from there. I feel for ya

It goes that way sometimes in life right?
I'm just trying to make the best of it.
I really want this barrel to JUST GO AWAY.

edit: Barrel is sold, yayyyyyyyyy...

Randall

Quoted: Anyone? Or should I just buy a colt 6520 and have it cut back?

If "government profile" will do, then check out www.ar15.com/forums/topic.html?b=7&f=22&t=270312

I bought a 20" 1/7 government profile from them.  From the time I mailed a check to the time I received the barrel was about a week.

Quoted: If "government profile" will do, then check out www.ar15.com/forums/topic.html?b=7&f=22&t=270312

Note that a bushmaster will not have an "F" marked front sight base or M4 feedramps like the Colt or LMT barrels will.
I'm not even sure that the 6520 is the "F" height either as it's an A1 FSB right?

For those that might not be away of the differences, "F" marked means it is 0.040" taller and proper for use with a flattop receiver.
I believe that the 6520 is an A2 receiver and therefore, the A1 FSB would be correct.
You can use an A2 FSB with a flattop, but you will need to change the front sight post to one that is 0.040" extra tall and then you lose the benefit of the sight protector ears as the front sight will just stick out the top above the ears now.

Randall

Quoted: Note that a bushmaster will not have an "F" marked front sight base or M4 feedramps like the Colt or LMT barrels will. I'm not even sure that the 6520 is the "F" height either as it's an A1 FSB right? For those that might not be away of the differences, "F" marked means it is 0.040" taller and proper for use with a flattop receiver. I believe that the 6520 is an A2 receiver and therefore, the A1 FSB would be correct. You can use an A2 FSB with a flattop, but you will need to change the front sight post to one that is 0.040" extra tall and then you lose the benefit of the sight protector ears as the front sight will just stick out the top above the ears now. Randall

I have a 6520. It is a "pencil" barrel, and has a A1 front sight base (.625), but has a A2 sight post installed. The 6520 has a 16" barrel, and the upper receiver is an A2. There is no "F" marking.


I am going to swap out the A2 for a CMT flattop w/ M4 cuts (6520 has M4 feedramps). This will be used with a Troy BUIS.


If it works out and zero's fine - great. If it is a too low, I have a few options. I can try and max out the elevation, and see if that gives me an acceptable zero, or I can get the taller front sight post from Bushmaster. Either way, 0.04 isn't that much, and I don't expect it to stick out of the protective wings on the front sight base. I could be wrong since I've never used this taller post, but of the sights I've zero'd, I've never had to go more than 2-3 "clicks" max. I am not so concerned with the irons having a specific short range zero.


The main sighting system will be an Aimpoint Comp C3 with Larue mount zero'd at 50y, so the irons are primarily a BUIS. The "mission" for this rifle will be 50-100 yards typically, 200 yards max. The 223 in any weight or velocity is a very flat shooting cartridge. Add the fact that I am looking for minute of badguy rather than having a precise iron-sight zero at short ranges. Bad guys are usually vertical targets, 5" up or down is meaningless when it comes to COM hits out to 100-150 yards anyhow.

Chances are, I'll leave it as is.

Quoted: Anyone? Or should I just buy a colt 6520 and have it cut back?

I just got a 6520. It is .625" the whole length. (actually, I haven't measured, but I think there is a slight taper in the profile under the handguards that may go slightly under .625 - just like the 20" govt profile which gets down lower than .625 at its narrowest point)


As a result, I wouldn't know where you could get the M4 "cut". That is, if you want the grenade launcher cut out.


The 6520 barrel extension is indeed cut for M4 feedramps. I find your request strange. Are you looking for the absolute lightest? I can tell you that this barrel is hard to beat for a chrome lined, 1/7, M4 feedramped barrel that is LIGHT. The only barrel that might equal it, or might be maybe 1oz lighter could be the Bushmaster super light, but that doesn't have M4 ramps. This barrel is so light, you won't feel the need to cut it back.


If you absolutely need the shorter barrel for some sort of CQC use....well if 1.5" is that important, why not go 10.5? either way (14.5 or shorty) you're doing the registered SBR route. Otherwise a permanently attached FH will negate any length saving (practically speaking).


Get the 6520. When you shoulder it, you will know what I am talking about. You will not want to change anything about the barrel. You'll find it ultra-light and short enough. Only thing I am changing on the 6520 is going from an A2 to flattop.


The weight savings going from 16 to 14.5 isn't much. You save the weight in the profile, not the length (unless its a big difference in length).

Quoted: As a result, I wouldn't know where you could get the M4 "cut". That is, if you want the grenade launcher cut out.

There is no need for the M4 grenade launcher step-down on a 6520 barrel as that barrel's diameter along it's whole length is the same diameter as a step-down area on an "M4" barrel