Here it is. My first Colt. Only change is I yanked the crappy A2 grip and slapped on a Hogue. The virtues of the light weight barrel came to me after a few carbine classes last summer where my RRA entry tactical just killed physically because it was a brick.

There is also a guy (Hired_Gun) that used to post here that is now in Iraq with a private security company, protecting humanitarian aid stations from insurgents. He tossed his RRA Entry Tactical and picked up a 6520 and says it's much better for standing all day. In his words, "The extra two pounds is two hundred pounds after a long day of sentry and security work"

I basically copied his configuration and took his advice. Anyway, on to the pics. These were taken after it was cleaned up. It was covered in some brown slime that was like syrup at first













Here is an interesting thing I noticed. Dremeled Feed ramps??!!! ON A COLT!?!?! I was under the impression that Colt never did this. Not that I care, because my RRA has the same, but for all the fuss some people make about Colt's using "real M4 ramps" and never a hack job I was surprised. Then again my lower isn’t stamped M4 so whatever...

Very nice!

Yup, just like mine.

Your Lower wont be stamped M4,  look right in back of the Delta Ring on the very front of the upper reciever, just above the gas tube.

That is where the M4 stamping should be

Quoted: Your Lower wont be stamped M4,  look right in back of the Delta Ring on the very front of the upper reciever, just above the gas tube. That is where the M4 stamping should be

It isnt. But I am guessing it is because it is an A2 and Colt doesnt currently make an A2 M4. Which would might also explain the "Hack Job" feed ramps

I just pulled my 6520 out o the safe and the feedramps look the same as yours.  Mine was made in 1998. Reliability and Feeding has always been 100%

Too nice to be dremel. Probably done in a fixture on a drill press. I'm guessing regular non-F front sight?

I take it this is a LGC 030,000 series?  Am curious, in that I added your rifle to the data base, but am not sure where it goes:

www.ar15.com/forums/topic.html?b=3&f=118&t=270259

The Diemaco bolt is pretty cool, those are not at all common.  Is the carrier the full auto type?  What is the upper forge code?  Does the bolt have a M4 extractor, black buffer with gold spring?

In regards to your feedramps, they are not dremeled, your looking at an A2 upper receiver that was machined to M4 specs after finishing.  Not that uncommon for Colt.  RRA feed ramps are a different animal, in thier own words:

Quoted: We make NO assertion that they are M4 feed ramps, or that we use M4 extensions, because they aren't and we don't, and never have.

These feed ramps were intended for two different purposes:

Quoted: We have, if you will go back and look at previous posts on the issue of the ramp extensions, we made no bones about why we break that edge...to help in feeding hollow point and soft point ammo.

BLACK RIFLE II page 70

Because of the higher bolt velocity and the resulting more rapid forward motion of the feeding cartridge, the nose of the heavier M855 bullet did not have time to rise high enough to enter one or other of the feed ramps on the barrel extension, and the bullet noses were stubbing on the upper receiver under there barrel extension, causing failures to feed...... To cope with this, the angle on the feed ramp cuts in the barrel extensions was altered form 45 degrees to 52 degrees, and the two half-moon ramps cuts were themselves extended down into the vertical face of the upper receiver, below the barrel extension.

Variablebinary: "Here is an interesting thing I noticed. Dremeled Feed ramps??!!! ON A COLT!?!?! I was under the impression that Colt never did this. Not that I care, because my RRA has the same, but for all the fuss some people make about Colt's using "real M4 ramps" and never a hack job I was surprised. Then again my lower isn’t stamped M4 so whatever..."


Was looking at my upper (Colt Match Target Competition HBARII) from 1998, and the feed ramps look identical to yours, except mine seem to line up with the extension much better. This might be an optical delusion, but yours seem to be slightly off-center from the extension....

Nice rifle..... my next rifle is going to have a lighter barrel on it, same as yours.... The HBAR is too much a heavyweight....

Quoted: I take it this is a LGC 030,000 series?  Am curious, in that I added your rifle to the data base, but am not sure where it goes: www.ar15.com/forums/topic.html?b=3&f=118&t=270259 The Diemaco bolt is pretty cool, those are not at all common.  Is the carrier the full auto type?  What is the upper forge code? In regards to your feedramps, they are not dremeled, your looking at an A2 upper receiver that was machined to M4 specs after finishing.  Not that uncomon for Colt.  RRA feed ramps are a different animal, in thier own words: Quoted: We make NO assertion that they are M4 feed ramps, or that we use M4 extensions, because they aren't and we don't, and never have.

It is a 030,000. Keyhole mark on upper which I think is Cerro forge. Thanks for the info on the feedramps.

To be honest I cant tell the difference between a full auto carrier or semi carrier. Tell me what to look for and I can tell you which it is.

Quoted: It is a 030,000. Keyhole mark on upper which I think is Cerro forge. Thanks for the info on the feedramps. To be honest I cant tell the difference between a full auto carrier or semi carrier. Tell me what to look for and I can tell you which it is.

Thanks for the info, got yours in the data base.

I added a few more questions, and feed ramp info to my post, before I saw your reply.  Far as a semi verses full auto carrier, will try and post pics tomorrow, unless someone beats me to it...

Oh yeah, congrats on the cool carbine.

Quoted: It isnt. But I am guessing it is because it is an A2 and Colt doesnt currently make an A2 M4. Which would might also explain the "Hack Job" feed ramps

 

Quoted: Quoted: It is a 030,000. Keyhole mark on upper which I think is Cerro forge. Thanks for the info on the feedramps. To be honest I cant tell the difference between a full auto carrier or semi carrier. Tell me what to look for and I can tell you which it is. Thanks for the info, got yours in the data base. I added a few more questions, and feed ramp info to my post, before I saw your reply.  Far as a semi verses full auto carrier, will try and post pics tomorrow, unless someone beats me to it... Oh yeah, congrats on the cool carbine.

Can I assume that MPD is Colt Canada/Diemaco, while a Colt USA bolt would be MPC?

Also are there any parts on current Colt weapons that will not interchange with parts from other companies?

Quoted: Can I assume that MPD is Colt Canada/Diemaco, while a Colt USA bolt would be MPC?

Yes

Also are there any parts on current Colt weapons that will not interchange with parts from other companies?

You have .170 fire control pins and trigger group parts. Other than that, no.

Quoted: I added a few more questions, and feed ramp info to my post, before I saw your reply.  Far as a semi verses full auto carrier, will try and post pics tomorrow, unless someone beats me to it... Oh yeah, congrats on the cool carbine.

Nice carbine indeed!!

here is your semi vs. auto carrier photo

Quoted: I really like the Govt Carbines. I wish I could get more...

I wish I could get ONE

Ahhhh, the beauty of the 6520......I love mine and pretty much everyone I know with one loves theirs!!!

Enjoy it!!!

I would like to offer you some more insight to what you are seeing. The model that you have uses the standard M16A2 upper receiver and standard rifle front sight base. Colt makes VERY few weapons with the fixed rear sights. I believe the upper receiver you have is a stock M16A2 upper that they place in a fixture to cut the extended ramps (not with a dremel tool) so they may be able to use their current production barrel extensions. THis will give you the enhancement of the extended feed ramps.

Colt's main production are Flat Top upper receivers. Those will be marked "M4". THe fixed carrying handle will not be marked, due o the fact that that receiver will not go with the flat top front sight assembly. I do not believe you have anything to be concerned with. I think this is a production reality for Colt that it makes more sence to modify M16A2 upper receivers considering the very few they produce rather than have large production lots of specific A2 carbine upper receivers. This will not degrade the quality by no means in terms of proformance or value.

Hope this helps.

Quoted: Too nice to be dremel. Probably done in a fixture on a drill press. I'm guessing regular non-F front sight?

I believe that is an F FSB.

The F will be on the port side. The F-marked FSB's I own have the #2 on the side shown in the photo above.

Quoted: Quoted: Too nice to be dremel. Probably done in a fixture on a drill press. I'm guessing regular non-F front sight? I believe that is an F FSB. The F will be on the port side. The F-marked FSB's I own have the #2 on the side shown in the photo above.

THat #2 is a vendor/die mark. Not an indication of the configuration of the FSB. Same vendors make both standard and F FSBs.

Aint it amazing when you realize how much lighter the Government Carcines are.

The Tactical Carbines have a hell of a roll mark but become very heavy when you have to actually use it all day.

Wont have the "F" marked FSB

My second favorite configuration, right behind the 6320 with it's C7/A1 sights

Quoted: Aint it amazing when you realize how much lighter the Government Carcines are. The Tactical Carbines have a hell of a roll mark but become very heavy when you have to actually use it all day. Wont have the "F" marked FSB My second favorite configuration, right behind the 6320 with it's C7/A1 sights

+1 - I'm still trying to piece one togther myself. The ultimate KISS carbine.

6520's with dremeled feedramps is not anything new but they are not all like that. Colt does make some A2 uppers (and A1\C7) uppers with properly machined\anodized feedramps

I am guessing it is because it is an A2 and Colt doesnt currently make an A2 M4. Which would might also explain the "Hack Job" feed ramps

I have a pre-ban 6520, 4 digit serial number, 65XX, that has annodized M4 feedramps and is marked "M4" on the barrel extension. This has always been what I would consider my SHTF rifle.
A lot of us talk about a "SHTF" rifle, but down here in south Louisiana, we actually praticed this in the aftermath of Hurricane Katrina. God bless the poor soul that tried to loot my home as Louisiana has a State Law, "Shoot the Burglar." No jokes from the state or me.

Bill

What are the gold discoloration on the ramps?  Brass from ammo riding the ramps?

Colt does make some A2 uppers (and A1\C7) uppers with properly machined\anodized feedramps

+1

Quoted: Colt does make some A2 uppers (and A1\C7) uppers with properly machined\anodized feedramps +1 home.comcast.net/~gocartmozart/Colt_6520.jpg home.comcast.net/~gocartmozart/Colt_6520_b.jpg home.comcast.net/~gocartmozart/colt_6520_c.jpg home.comcast.net/~gocartmozart/M4_ramps1.jpg home.comcast.net/~gocartmozart/M4_ramps2.jpg home.comcast.net/~gocartmozart/M4_ramps3.jpg

What carbine configuration is that? I dont have a 4 mark anywhere on my upper nor on the barrel extention.

Cant believe I'm getting sucked into Colts. I need to run out and get a bushmaster or something to curtail this Pony fever

Quoted: Quoted: Colt does make some A2 uppers (and A1\C7) uppers with properly machined\anodized feedramps +1 home.comcast.net/~gocartmozart/Colt_6520.jpg home.comcast.net/~gocartmozart/Colt_6520_b.jpg home.comcast.net/~gocartmozart/colt_6520_c.jpg home.comcast.net/~gocartmozart/M4_ramps1.jpg home.comcast.net/~gocartmozart/M4_ramps2.jpg home.comcast.net/~gocartmozart/M4_ramps3.jpg What carbine configuration is that? I dont have a 4 mark anywhere on my upper nor on the barrel extention. Cant believe I'm getting sucked into Colts. I need to run out and get a bushmaster or something to curtail this Pony fever

it is the R6520. with the GC serial prefix.  

not the L GC serial prefix that are on the cuurent gov't carbines

I bought two 6520s last year and both had feedrampls identical to the original poster.  I say "had" because I changed one out to a flattop and ninja-ized it.

As for the "F" FSB, the 6520 does not have an "F" FSB.  That would make no sense as the "F" is intended for theflattop.  When I changed my upper to a flattop I went with a 9.0 rail, shaved the stock FSB, and installed a Troy front BUIS.  A standard "F" FSB won't work on the the 6520's skinny barrel.  You'd have to find a 6933 FSB to get it to work.

Quoted: I bought two 6520s last year and both had feedrampls identical to the original poster.  I say "had" because I changed one out to a flattop and ninja-ized it. As for the "F" FSB, the 6520 does not have an "F" FSB.  That would make no sense as the "F" is intended for theflattop.  When I changed my upper to a flattop I went with a 9.0 rail, shaved the stock FSB, and installed a Troy front BUIS.  A standard "F" FSB won't work on the the 6520's skinny barrel.  You'd have to find a 6933 FSB to get it to work.

I wish colt would take the 6933 and make a derivative with a 16" barrel.

16" 1/7 twist pencil barrel, flat top, F-sight block, factory gun goodness.  i can almost taste it.

Quoted: I wish colt would take the 6933 and make a derivative with a 16" barrel. 16" 1/7 twist pencil barrel, flat top, F-sight block, factory gun goodness.  i can almost taste it.

I agree.  Barring that, I had to build my own.  I frankly would have much rather used the stock FSB and a DD 9.5 cut down to 9.0 length, but I had to make do with what I could find.

I suspect that someone like SAW could get them to make what we want, but it would be some sort of limited run.  Colt makes all the parts, we just have to get them to put them all together in the right package.

I wish colt would take the 6933 and make a derivative with a 16" barrel. 16" 1/7 twist pencil barrel, flat top, F-sight block, factory gun goodness. i can almost taste it

I agree.  The carbine pictured below has everything you listed except the "F" sight block; a 0.40" higher front sight post takes care of that.  This carbine weights 6.25 lbs with the LMT Crane SOPMOD stock.

Quoted: I wish colt would take the 6933 and make a derivative with a 16" barrel. 16" 1/7 twist pencil barrel, flat top, F-sight block, factory gun goodness. i can almost taste it I agree.  The carbine pictured below has everything you listed except the "F" sight block; a 0.40" higher front sight post takes care of that.  This carbine weights 6.25 lbs with the LMT Crane SOPMOD stock. home.comcast.net/~gocartmozart/Colt_16_flattop.jpg

nice gun.  if you want a carry handle and are up for a challenge in trying to find one.

Some of the early colt carry handles (MMA forge code) were mahined with a lower sight shelf to work with A2 sight blocks and flat top uppers.  They are also distinctive in that they sat up off the rail at the rear leaving a air gap.  

You will find several variations in Colt production. Depending on when they made the guns. Early on, prior to the assault weapon ban, Colt produced the Sporter Lightweight, these were large runs of commercial guns. I have a couple examples that show extended feed ramps. With Colt putting a vast majority of their production in government guns, I do not believe they continued to manufacture any significant numbers of these fixed sight upper receives. I will be checking next week.
   Througout my research over the last 10 years or so it has been difficult to catalog all variations of things coming out of Colt. There were many limited run as well as one time run things. Diffrent methods of marking them as well as things changing based off the immediate needs of the company. During research I did find some documentation in Colt's archives of "4" being stamped alone. This is documented in BR2. But it was unclear weather this was short for M4 or had any other meaning. If any of you have any Sporter Lightweight carbines take a look and see if that 4 is present. Let us know. I would be nice to add this to a list with a meaning. Can not do much with only one sample.
    I do not believe that having feed ramps cut into the recever is a hack job if done properly. Ken Elmore has a fixture at SAW to modify upper receivers to this configuration. This is not done by hand but to specifications. I would not feel cheeted in any way. The gun you have is not one of the more common guns built by COlt anymore.The PD's do not want fixed sights anymore. THere is little demand for any receiver other than the flat top these days other thn replacement parts for government A2 rifles. These are more civillian guns than LE. Considering the cost to produce and store large numbers of receivers that can not be used with sandard barrel extensions, it makes sence to have a universal upper receiver that can be used in a rifle or with a simple and quik mod, into a carbine.
   I am gathering more data for a revision of BR2. THese are the types of things I am looking for. Any further info you guys can provide on this "4" mark would be useful.

Chris

Quoted: You will find several variations in Colt production. Depending on when they made the guns. Early on, prior to the assault weapon ban, Colt produced the Sporter Lightweight, these were large runs of commercial guns. I have a couple examples that show extended feed ramps. With Colt putting a vast majority of their production in government guns, I do not believe they continued to manufacture any significant numbers of these fixed sight upper receives. I will be checking next week.    Througout my research over the last 10 years or so it has been difficult to catalog all variations of things coming out of Colt. There were many limited run as well as one time run things. Diffrent methods of marking them as well as things changing based off the immediate needs of the company. During research I did find some documentation in Colt's archives of "4" being stamped alone. This is documented in BR2. But it was unclear weather this was short for M4 or had any other meaning. If any of you have any Sporter Lightweight carbines take a look and see if that 4 is present. Let us know. I would be nice to add this to a list with a meaning. Can not do much with only one sample.     I do not believe that having feed ramps cut into the recever is a hack job if done properly. Ken Elmore has a fixture at SAW to modify upper receivers to this configuration. This is not done by hand but to specifications. I would not feel cheeted in any way. The gun you have is not one of the more common guns built by COlt anymore.The PD's do not want fixed sights anymore. THere is little demand for any receiver other than the flat top these days other thn replacement parts for government A2 rifles. These are more civillian guns than LE. Considering the cost to produce and store large numbers of receivers that can not be used with sandard barrel extensions, it makes sence to have a universal upper receiver that can be used in a rifle or with a simple and quik mod, into a carbine.    I am gathering more data for a revision of BR2. THese are the types of things I am looking for. Any further info you guys can provide on this "4" mark would be useful. Chris

Upper receivers marked "4" are common in 1993-95 production 6520, 6721, and 6731 carbines.  Have not gotten very far with putting together a LW data base, but am sure they used the same upper receiver as did the 6520.  Here are the 6520 and 6721 data bases (6731 is not posted yet):

6520

www.ar15.com/forums/topic.html?b=3&f=118&t=270259

6721

www.ar15.com/forums/topic.html?b=3&f=118&t=271173

Quoted: When I got out of the Marines in the late 1980's, the first AR I ever bought was a Colt 6520. Great Light Weight Carbine!!   Still got it and will never sell it. enjoy!

I have to agree. So light and simple and built well. There isnt anything not to like really

Quoted: You will find several variations in Colt production. Depending on when they made the guns. Early on, prior to the assault weapon ban, Colt produced the Sporter Lightweight, these were large runs of commercial guns. I have a couple examples that show extended feed ramps. With Colt putting a vast majority of their production in government guns, I do not believe they continued to manufacture any significant numbers of these fixed sight upper receives. I will be checking next week.    Througout my research over the last 10 years or so it has been difficult to catalog all variations of things coming out of Colt. There were many limited run as well as one time run things. Diffrent methods of marking them as well as things changing based off the immediate needs of the company. During research I did find some documentation in Colt's archives of "4" being stamped alone. This is documented in BR2. But it was unclear weather this was short for M4 or had any other meaning. If any of you have any Sporter Lightweight carbines take a look and see if that 4 is present. Let us know. I would be nice to add this to a list with a meaning. Can not do much with only one sample.     I do not believe that having feed ramps cut into the recever is a hack job if done properly. Ken Elmore has a fixture at SAW to modify upper receivers to this configuration. This is not done by hand but to specifications. I would not feel cheeted in any way. The gun you have is not one of the more common guns built by COlt anymore.The PD's do not want fixed sights anymore. THere is little demand for any receiver other than the flat top these days other thn replacement parts for government A2 rifles. These are more civillian guns than LE. Considering the cost to produce and store large numbers of receivers that can not be used with sandard barrel extensions, it makes sence to have a universal upper receiver that can be used in a rifle or with a simple and quik mod, into a carbine.    I am gathering more data for a revision of BR2. THese are the types of things I am looking for. Any further info you guys can provide on this "4" mark would be useful. Chris

I have a 6520 with the SN LGC0297XX, "4" on the front of the upper, and annodized extended feedramps. Also, 4 at the three o'clock position on the front of the barrel extension.

I have a 5.56 Colt Sporter LW, SN SL0208XX with "4" stamped on the upper, annodized extended feedramps, "4" stamped at three O'clock on the front of the barrel extension.


BTW, to Variablebinary, after re-reading many of your previous posts, it seemed that you were laying anchor and staying on [that other brand]-island.  What changed your course?

I have a 6520 in the 3500x range. It has the non-finished feedramps. My guess is that Colt is taking regular finished A2 uppers and cutting M4 ramps into them. My A2 Colt upper was not marked "C" at all, but it did have the black ejection port spring found on Colts.


I swapped out the A2 for an A3 with M4 ramps (CMT from Bravo Co.) so that I could slap on a Troy BUIS and a Larue/Aimpoint. Now I hace a very light A3 uppered pencil barrel in 1/7.


Rifle has been flawless through 500 rounds and no cleaning (with Wolf being 1/2 of that)

Quoted: Quoted: When I got out of the Marines in the late 1980's, the first AR I ever bought was a Colt 6520. Great Light Weight Carbine!!   Still got it and will never sell it. enjoy! I have to agree. So light and simple and built well. There isnt anything not to like really

Except the price........

Quoted: BTW, to Variablebinary, after re-reading many of your previous posts, it seemed that you were laying anchor and staying on [that other brand]-island.  What changed your course?

Hired_Gun was a member of ARFCOM that works with a private security company. Due to a very strict NDA he is no longer allowed to post here. He turned me on to the 6520 which he now uses in Iraq guarding humanitarian aid stations.

In his words, "The extra two pounds is two hundred pounds after a long day of sentry and security work".

I learned this during carbine training. RRA barrels are nose heavy and stress the support arm heavily

2nd: I dont trust anyone else to make a lightweight except colt. The only other option is Bushmaster which I havent had the best of experiance with, and while CMMG is good, I thought Colt offered more for just a few dollars extra.

Quoted: Quoted: BTW, to Variablebinary, after re-reading many of your previous posts, it seemed that you were laying anchor and staying on [that other brand]-island.  What changed your course? Hired_Gun was a member of ARFCOM that works with a private security company. Due to a very strict NDA he is no longer allowed to post here. He turned me on to the 6520 which he now uses in Iraq guarding humanitarian aid stations. In his words, "The extra two pounds is two hundred pounds after a long day of sentry and security work". I learned this during carbine training. RRA barrels are nose heavy and stress the support arm heavily 2nd: I dont trust anyone else to make a lightweight except colt. The only other option is Bushmaster which I havent had the best of experiance with, and while CMMG is good, I thought Colt offered more for just a few dollars extra.

Excellent, any optic plans for the Colt? I know the RRA M4 cut is typically heavy under the handguards. How much weight would you lose if that was trimmed? I have 5 of the 6520's. and as has been said b4, LOVE has set in! It consumates the original intent of the platform IMO.

Quoted: Quoted: Quoted: BTW, to Variablebinary, after re-reading many of your previous posts, it seemed that you were laying anchor and staying on [that other brand]-island.  What changed your course? Hired_Gun was a member of ARFCOM that works with a private security company. Due to a very strict NDA he is no longer allowed to post here. He turned me on to the 6520 which he now uses in Iraq guarding humanitarian aid stations. In his words, "The extra two pounds is two hundred pounds after a long day of sentry and security work". I learned this during carbine training. RRA barrels are nose heavy and stress the support arm heavily 2nd: I dont trust anyone else to make a lightweight except colt. The only other option is Bushmaster which I havent had the best of experiance with, and while CMMG is good, I thought Colt offered more for just a few dollars extra. Excellent, any optic plans for the Colt? I know the RRA M4 cut is typically heavy under the handguards. How much weight would you lose if that was trimmed? I have 5 of the 6520's. and as has been said b4, LOVE has set in! It consumates the original intent of the platform IMO.

Colt 6920 5.95 +/- 6lbs
RRA Entry Tactical  7.5lbs
Colt 6520 5.8

M4 profile saves weight, but the 6520 balances better IMHO . It moves the weight toward the middle of the gun instead of nose, so it swings better. I could have purchased a 6920 but I dont think I will ever have a grendade launched mounted, and every ounce saved in the gun means survivng cabine class better and more bullets carried. I've head that pencil A1 barrels used to bend under pressure because they were used as can openers and back scratchers. I honestly dont know how durable the pencil barrel is, but it sure is a joy to handle.

To be honest if I had ever handled a 6520 in the past I would never have bothered with the M4 configuration at all. I just assumed they were weak and skipped the lightweight config completely. Live and learn

I plan to leave it stock, no optics which is why I opted for an A2. I have a precison AR15 in the works for killing stuff at 400 yards. Pics of that soon I hope

Don't feel bad, you're not alone.   They may look ugly, but they run 100%.

Colt does make A2 uppers with M4 ramps... as the photo shows.  Huh.  Nice rifle though, and interesting that it looks like a lot of Colts seem to be showing up with Diemaco parts these days.

I wish there was a greater variety of lightweight profile barrels available.  A 16" mid would be nice.

Is that the super light-weight barrel?