Can anyone recommend the best Colt lower for this build??

Are you asking regarding the offsize FCG pins, different front pins sizes, or about the markings on the side?

Well, I have the Colt A4 upper already and the pins have to be the small push pins.  So taking that into account, and I guess overall, the stock, markings on side, etc...  I'm trying to go as close to real as any civilian can I guess...  Any ideas??

Does your current upper have the M4/ enhanced feedramps?

Quoted: Does your current upper have the M4/ enhanced feedramps?

Yep, I checked as soon as I received it and there they were...  However, "enhanced" I have no idea...  It looks just like the Colt M4 FR's though...

I thought that A4's had rifle feedramps...??

Quoted: I thought that A4's had rifle feedramps...??

I really didn't get close enough to see that much of a difference between M4 and rifle feedramps.  I only glanced at it when I got it.  After that I brought it to a buddy of mine to install a 12" Larue.  When I get it back in a couple days I'll look more closely.

Oh, I'm not exactly sure either bro.  When I was issued an A4, I didn't even know what a feedramp was (until ARFCOM chewed it death).  The Bravo Co. 20in upper I've got has m4 feedramps.  Slapped an m5 RAS and a ta31frco on there and voila, a4gery...

Well, I'm wondering what is the best Colt lower for my A4gery upper??  I really don't care about the feedramps that much...  

Quoted: Well, I have the Colt A4 upper already and the pins have to be the small push pins.  So taking that into account, and I guess overall, the stock, markings on side, etc...  I'm trying to go as close to real as any civilian can I guess...  Any ideas??

If you can find a 6721 lower, I think you would like it... The roll marks on the side of mine makes me smile everytime I look at them...

I'll get a pic for you in a bit so you can take a look...

Quoted: Well, I'm wondering what is the best Colt lower for my A4gery upper??  I really don't care about the feedramps that much...

Wait a minute, your upper receiver is going to have grooves cut that run the bullet nose under your barrel extension, and you are more concerened about how your lower looks?


I really don't understand this overall thought process....

The 6721 lower is nice, but if you are worried about the markings, your rifle will say carbine.

That was pretty quick stick... I went to upload a pic using uploadx and they now want you to register to use their services... Did what I had to do and came back to add it to my post and here you are...

Your pic is much nicer than the ones I have...

You also made me realize something, he said A4 not M4... Damn, He needs a rifle roll marked lower like a sporter model not one that has carbine on it...

Quoted: Well, I have the Colt A4 upper already and the pins have to be the small push pins.  So taking that into account, and I guess overall, the stock, markings on side, etc...  I'm trying to go as close to real as any civilian can I guess...  Any ideas??

Find a White Label lower... Manufactured around 89-90...

Wait a minute, your upper receiver is going to have grooves cut that run the bullet nose under your barrel extension, and you are more concerened about how your lower looks?


Your absolutely right.  I didn't even think of that.  No, the way it looks is only one aspect.  What's most important is to have the A4 upper be compatible in its rifle configuration with the lower.  That's paramount of course and is essentially the reason behind me asking for any advice in the first place.  I'm just lacking the terminology and understanding to to express what I need in detail.

So do you think a Colt Sporter model lower would be my best bet???  

I heard the White Label lowers are extremely rare!!  Is that the closest I can get to an A4gery????

Quoted: That was pretty quick stick... I went to upload a pic using uploadx and they now want you to register to use their services... Did what I had to do and came back to add it to my post and here you are... Your pic is much nicer than the ones I have... You also made me realize something, he said A4 not M4... Damn, He needs a rifle roll marked lower like a sporter model not one that has carbine on it...

Yea your right.  I already have a 6721 and I swapped out the barrel for a 14.5 SOCOM with perm FH.  The weapon is SWEET!

The problem is that most of the recent Colt lowers are all large FCG holes.  Go back farther in time, and most are large front take down pin holes.  Eventually, you get to a time where things were semi-normal for Colt with their products, but its not exactly easy to find them.

Take a good look at how important certain features are to you.  None of them are going to say Colt M16A4, so after a certain point, you are batting your head against the wall for wording.  Maybe one of the lowers that says Match Target would work for you, but then again, maybe not.

I can't really think of a "best" lower that looks like it would fit for you.  I like Colt, but I don't worship at the Colt Temple, its very possible that one of the Colt fans will have better info  for you.  

Quoted: Yea your right.  I already have a 6721 and I swapped out the barrel for a 14.5 SOCOM with perm FH.  The weapon is SWEET!

I started out with just the lower and built the flat top upper using a mid weight SOCOM 14.5" barrel with a Vortex FH...

Yeah, your right about the white labels, you have a better chance of hitting the million dollar lotto before finding one of those...

I wish I could of been a little more helpful but these COLTS differ so damn much its hard to decide what would work for you... Good luck in finding what your after...

No, its cool.  I'm taking my time with this build.  No rush for me whatsoever.  I already have 3 AR carbines and want at least 1 AR rifle, but I'm sure it will quickly multiply too.  By the way, where in Pa are you located???  I'm just outside Phila.  

Buy an M16A2 and have a "4" stamped over the "2"

Quoted: By the way, where in Pa are you located???  I'm just outside Phila.

25 miles southwest of Pittsburgh...

Quoted: The problem is that most of the recent Colt lowers are all large FCG holes.  Go back farther in time, and most are large front take down pin holes.  Eventually, you get to a time where things were semi-normal for Colt with their products, but its not exactly easy to find them. Take a good look at how important certain features are to you.  None of them are going to say Colt M16A4, so after a certain point, you are batting your head against the wall for wording.  Maybe one of the lowers that says Match Target would work for you, but then again, maybe not. I can't really think of a "best" lower that looks like it would fit for you.  I like Colt, but I don't worship at the Colt Temple, its very possible that one of the Colt fans will have better info  for you.

Okay Stick, forgetting about the external wording completely, what features SHOULD I be looking for in a A4gery lower?  I'm sure I want an A2 stock and of course smaller push pins.  Is there anything else internal that I need that would make it more compatible with this Colt A4 upper and more resembling an A4??

Quoted: Quoted: The problem is that most of the recent Colt lowers are all large FCG holes.  Go back farther in time, and most are large front take down pin holes.  Eventually, you get to a time where things were semi-normal for Colt with their products, but its not exactly easy to find them. Take a good look at how important certain features are to you.  None of them are going to say Colt M16A4, so after a certain point, you are batting your head against the wall for wording.  Maybe one of the lowers that says Match Target would work for you, but then again, maybe not. I can't really think of a "best" lower that looks like it would fit for you.  I like Colt, but I don't worship at the Colt Temple, its very possible that one of the Colt fans will have better info  for you.   Okay Stick, forgetting about the external wording completely, what features SHOULD I be looking for in a A4gery lower?  I'm sure I want an A2 stock and of course smaller push pins.  Is there anything else internal that I need that would make it more compatible with this Colt A4 upper and more resembling an A4??

if you don't care about it saying colt on it, you can get any manufacturers lower with an A2/A4 stock and it'll be correct.  They're all the same for the most part...

This would have been PERFECT...  Goddam Government...


http://gunbroker.com/Auction/ViewItem.asp?Item=42181381

I just picked up a Colt Lower CR6724 marked CAR-A3 elite w/ elite trigger for my A4gery.  Wanted to know what you guys think with this choice???

Quoted: This would have been PERFECT...  Goddam Government... http://gunbroker.com/Auction/ViewItem.asp?Item=42181381

If you are worried about the correct "look", that lower would be all wrong for a M16A4gery but with a happy switch I'm sure you wouldn't have cared!

I don't know why Stickman is asking you about the feedramps as they have nothing to do with the lower and either "rifle" or "M4" ramps are fine. "M4" ramps while nice to have but are generally over-rated.

Functionally...
Considering you specified it must be a Colt lower then the only 2 functional points to consider.
1. Take down pin size. You obviously want a lower that has the small take down pins.
2. Sear block. If your M16A4 upper came with a M16 bolt carrier then you do not want a Colt lower with the pinned in sear block. Reason being that sear block will interfere with a full auto carrier.

Stock wise...
Yes, for a M16A4gery you want an A2 fixed stock but don't worry about it. If the lower you buy does not have one, sell what ever stock it does have and install a A2 fixed unit. No big deal.

Looks wise...
You are not going to find a Colt lower that is marked in any way that would be considered correct, or even close to correct for an M16A4gery. Older Colts have a grayish anodizing. Newer ones are black. For you purpose, you want a black one. Roll marks are a personal thing so if you find one that floats your boat and the lower meets all of the other criteria then you should be good to go.

Me personally, if I'm going to shell out premium money for a "Colt" lower then it better also say "AR15" because that's the name that seems to really piss off the liberal gun grabbers.

There is only 3 Colt lowers currently available from Colt that have the AR15 roll-mark.

AR6450 -
Marked
AR-15 9mm Carbine

AR6721 - (My favorite)
Marked
AR-15A3
Tactical Carbine

AR6520 -
Marked
AR-15 A2
Gov't Carbine

For your project, I would get a 6520 lower. Good luck

Quoted: I just picked up a Colt Lower CR6724 marked CAR-A3 elite w/ elite trigger for my A4gery.  Wanted to know what you guys think with this choice???

That's a nice lower.

Does it have a hole for the detent pin and spring of the take down pivot pin?

If it does, it's perfect, but if not just have it put in by a competent gunsmith.

Quoted: I don't know why Stickman is asking you about the feedramps as they have nothing to do with the lower and either "rifle" or "M4" ramps are fine.

A-  I'm an ass who is here simply to cause hate and discontent

B-  I feel function is the most important thing when dealing with weapons


Take your pick.



If you make it a habit of misassembling weapons, that is your perogative, but it isn't mine.  If people want to get hurt feelings or sensitive, it really doesn't matter to me.  The people I deal with daily are depending on weapons, and I extend that same courtesy to those on this board.  You will have to forgive me for not considering that to some people these weapons are just toys and show pieces.

If you feel a M4 feedramp upper will feed fine into a rifle barrel extension, I will hope that other people note your comment, and remember it whenever they read anything else you write.  If I misunderstood your comment, please forgive me, but this board seems to be getting worse in regard to bogus information being spread here.

Quoted: If you feel a M4 feedramp upper will feed fine into a rifle barrel extension, I will hope that other people note your comment, and remember it whenever they read anything else you write.  If I misunderstood your comment, please forgive me, but this board seems to be getting worse in regard to bogus information being spread here.

I was thinking of doing this kind of build myself but I was just going to rebarrel a 6721 and replace the collapsible stock with a regular A2 stock. Now that I see this, my question is is there a way to fix this so that I can use the rifle barrel rather than the carbine barrel?

Match Target M4?

Quoted: Quoted: I just picked up a Colt Lower CR6724 marked CAR-A3 elite w/ elite trigger for my A4gery.  Wanted to know what you guys think with this choice??? That's a nice lower. Does it have a hole for the detent pin and spring of the take down pivot pin? If it does, it's perfect, but if not just have it put in by a competent gunsmith.

What exactly is this?  And how necessary is it??  Sorry for sounding like a novice here.  I'm not too savy with A4's...

In the attached photo look at the area behind (to the left side) of the pivot pin, you could see a small drain hole in the front end of the magazine fence forward extension.

There is also a hole between the pivot pin and the receiver which holds the detent pin and spring of the pivot pin, like the ones for the rear take down pin.

Military models usually have a front push pivot pin instead of the usual civilian two piece pivot pin.

The military style front pivot pin works also as a take down pin like the rear pin to remove the upper without uncrewing the pivot pin.

If you want to be authentic to the military model you want to have this feature. If you don't care about it the two piece screw type pivot pin is fine.

I have the military type push pivot pin in my Colt 6721 tactical carbine and LMT M4 Defender 2000 carbine, it makes upper replacement quick and easy.

Maybe you could show us a photo of your lower right side so we could see it.

Quoted: Quoted: Quoted: I just picked up a Colt Lower CR6724 marked CAR-A3 elite w/ elite trigger for my A4gery.  Wanted to know what you guys think with this choice??? That's a nice lower. Does it have a hole for the detent pin and spring of the take down pivot pin? If it does, it's perfect, but if not just have it put in by a competent gunsmith. What exactly is this?  And how necessary is it??  Sorry for sounding like a novice here.  I'm not too savy with A4's...

Quoted: Quoted: I don't know why Stickman is asking you about the feedramps as they have nothing to do with the lower and either "rifle" or "M4" ramps are fine. A-  I'm an ass who is here simply to cause hate and discontent B-  I feel function is the most important thing when dealing with weapons Take your pick.

I pick C- Stick to answering the question asked. The guy asked which lower he should get for a close as possible A4gery. Your first response for more info made complete sense. He then replies he already has an "A4" upper and that the upper has the small take down pins. You respond asking him if his upper has M4 feedramps?

WTF did feedramps have to do with what he was asking or what had been discussed so far? That was my point, you directing this thread in a direction that had nothing to do with what was asked.

Quoted: If you make it a habit of misassembling weapons, that is your perogative, but it isn't mine.  If people want to get hurt feelings or sensitive, it really doesn't matter to me.  The people I deal with daily are depending on weapons, and I extend that same courtesy to those on this board.  You will have to forgive me for not considering that to some people these weapons are just toys and show pieces.

WTF are you talking about??? Who mis-assembling what? He said he already has an "A4" upper. I guess you read that differently then I did? I took that to mean that he bought an assembled upper that has a flattop receiver and 20" gov't profile barrel. Why did you automatically assume that meant he has mismatched feedramps?

Quoted: If you feel a M4 feedramp upper will feed fine into a rifle barrel extension, I will hope that other people note your comment, and remember it whenever they read anything else you write.  If I misunderstood your comment, please forgive me, but this board seems to be getting worse in regard to bogus information being spread here.

Again, WTF are you talking about? Are we reading the same thread??? Who said it was OK to mismatch the barrel and upper? I said either M4 or rifle ext. are fine. IMO, it goes without saying that the ext. of the barrel and cuts in the upper need to match. If the guy was asking how to build an upper then I would have included that detail but considering it was obvious this upper was assembled by somebody else and again, this has nothing to do with what he was asking, I didn't feel the need to get that detailed about the feedramps.

I have no idea why you automatically assumed his barrel and receiver are mismatched?

Quoted: www.chameleonweaponry.com/dr-arf/RM_COLT_223_AR15A3_TACTICAL_CARBINE_FLIP_SIDE.jpg In the attached photo look at the area behind (to the left side) of the pivot pin, you could see a small drain hole in the front end of the magazine fence forward extension. There is also a hole between the pivot pin and the receiver which holds the detent pin and spring of the pivot pin, like the ones for the rear take down pin. Military models usually have a front push pivot pin instead of the usual civilian two piece pivot pin. The military style front pivot pin works also as a take down pin like the rear pin to remove the upper without uncrewing the pivot pin. If you want to be authentic to the military model you want to have this feature. If you don't care about it the two piece screw type pivot pin is fine. I have the military type push pivot pin in my Colt 6721 tactical carbine and LMT M4 Defender 2000 carbine, it makes upper replacement quick and easy. Maybe you could show us a photo of your lower right side so we could see it. Quoted: Quoted: Quoted: I just picked up a Colt Lower CR6724 marked CAR-A3 elite w/ elite trigger for my A4gery.  Wanted to know what you guys think with this choice??? That's a nice lower. Does it have a hole for the detent pin and spring of the take down pivot pin? If it does, it's perfect, but if not just have it put in by a competent gunsmith. What exactly is this?  And how necessary is it??  Sorry for sounding like a novice here.  I'm not too savy with A4's...

Well, I bought the Colt lower, but I didn't receive it yet.  I'm hoping to get it by the middle or late next week.  I'll make a note to post a pic when it arrives.  Thanks so much for your help!

Quoted: I don't know why Stickman is asking you about the feedramps as they have nothing to do with the lower and either "rifle" or "M4" ramps are fine. "M4" ramps while nice to have but are generally over-rated. Stick is referring to the fact that a non-M-4 extension in an M-4 cut upper is bad juju as it leaves an area under the extension that can catch the nose of the bullet.

That is correct and I already knew that. What I don't know is why Stickman asked him about the feedramps in the first place and why he's so convinced this guy is using a barrel with a "rifle" ext. in an upper cut for "M4" ramps? books hasn't really stated exactly what he has but again, it has nothing to do with what he asked about in the first place. That's all I'm saying.

You know what, whatever. It doesn't really matter at this point.

I don't have the upper on hand to look at the feedramps.  I brought it to a shop close by for them to install a Larue 12".  When I get it back I can possibly take a pic of the feedramps and post it.  Do any of you guys have a picture of rifle feedramps??  Or ideally, M4 feedramps side by side with rifle feedramps.  I'd like to see the difference.  If not, when I get the upper back I'll devote a post and ask again.  Thanks for all your help guys.  

If I remember  right, there is a gigantic thread about them and arguements about their usefulness somewhere, but it might be archived by now. It was 10-15 pages long, but the first page had tons of photos of them, including side by side comparisons. I can't find the link...

Books got the upper from me and I can assure everyone that it was built correctly. The Colt flat top upper receiver does NOT have M4 feed ramps or any other kind of feed ramps which is correct for M16A4 style rifle uppers. The barrel is actually a Colt green label era 20inch heavy barrel. It is chrome lined with a 1x7 twist and has factory installed flash hider and bayo lug. This barrel has a standard/regular rifle barrel extension NOT the M4 barrel extension. The barrel and upper are a perfect match designed to work together. Books, as for a lower I think the one you have coming is an excellent choice as those are small pin like the upper and the color should be black like the upper. Not to mention I really like the rollmark that lower has!