COLT AR-15A4 Lightweight LE Carbine

AR/M4 AR General Discussion
1

The LGS had a deal on the COLT AR-15A4 Lightweight LE Carbine (6720) so I went home and researched everything I could find on it overnight. After reading all of the threads here about it I decided to buy one. Once I got it home I ditched the OEM furniture and added some MOE stuff I had laying around.

It does not have an “F” marked FSB but I really don’t care. I don’t have the motivation to remove the site post and put it in a set of calipers but it does appear to look a smidge taller than a normal post. It has to be my imagination or some sort of optical illusion as I don’t think I could register such a small difference. Either way it’s a COLT and should run just fine.

For those that care it only came with a manual, lock, standard A2 grip/M4 handguards and MBUS. No mag since I live in Colorado and nobody trusts us with anything over 15 rounds. :mad:

The trigger is standard milspec but feels fine without the normal crunchiness of a new milspec trigger.

It has great balance and now I am kicking myself for not buying a LW AR before today. Looking forward to shooting the hell out of it very soon.

Need a DD fixed rear site or maybe an RDS like an Aimpoint Mirco or Trijicon RMR but want to keep this simple and light.

DD rear site added.

2

What did you pay for it? PSA has these on sale for $799 with free shipping from time to time.

LW ARs are awesome, as long as you’re not on an FOB in the sandbox.

3

I got mine for a little less than $800 OTD.

4

I use one of these as my “Vacation/travel” gun. Wait for the sales on Memorial day and pick up an Aimpoint PRO. These are great carbines.

5

The 6720 is a carbine - short, fast, there when you need it. Spectacular balance, minimalist presentation.
It feels closest to what Eugene Stoner had in mind 60 years ago.

6

Nice score! I have two, they are great KISS carbines.

7

Colt Front Sight Post Primer

Colt offers four different front sight posts for use on their AR-15/M16 family of weapons. The front sight posts can be categorized according to their basic shape, (square or round) their profile, (straight or tapered) and their height, (short or tall.) The height of the posts are measured from the top of the sight post down to the top of the “flange” of the sight post.

The sight post with the part number SP64507 has a short, square and straight configuration. This post has a nominal height of 0.270”

SP64507

Part number SP64665 also has a short and square post, but differs from the above sight post in that it has a tapered shape to it; broader at the base and narrowing at the top. The height of this post is also 0.270”.

SP64665

Shown below are the square, short/straight and short/tapered sight posts side by side for comparison.

The sight post associated with the M16/M16A1 series of rifles has a round shape and is also short and tapered. The part number for this post is SP61706. It is slightly shorter than the two posts described above with a height of 0.260”.

SP61706

The last sight post is Colt’s tall sight post which has a nominal height of 0.300”. It has a square and straight configuration. Its part number is SP62447.

SP62447

Here is a pic with the round sight post and the tall sight post side by side for comparison.

The original round sight post has five equally spaced notches around the sight post flange for elevation adjustment. Each notch corresponds to 1 MOA of elevation (when used with a rifle length sight radius). The other three sight posts all have four elevation notches on their flanges corresponding to 1.25 MOA of evlevation.

Bushmaster makes a front sight post that has a nominal height of 0.310”.

“F” Marked Front Sight Base

There is no difference in the overall height of an “F” marked front sight base and a standard front sight base. The only difference between the two front sight bases is the height of the sight “shelf” above the top of the barrel.

The front sight post on a standard Colt front sight base will bottom-out in the sight well at approximately 24 clicks below flush. On an “F” marked front sight base the sight “shelf” is a whopping 0.040” higher than on a standard front sight base. That means you might have to turn your front sight post down approximately 6 clicks further with an “F” marked front sight base than on a standard front sight base. (6 whole clicks difference. Oh, the inhumanity!) So unless your front sight post is set at 18 clicks below flush with a standard front sight base, using an “F” marked front sight base on a 20" barrel will be a non-issue.

…

8

That looks like the one in my rifle. I knew it looked different than all of the countless M4 front site posts I have seen.

Thanks for the excellent and informative information.

9

I have seen a huge amount of band width spent discussing and worrying about the different front sight post of the 6720 s. the 6920. Bottom line is that the front sight post shipped in your 6720 works well for your gun.

If you want to run just iron sights, then the MBUS rear will work. Although I might consider obtaining a Daniel Defense fixed rear.

I’m past the 50 year old mark and my eyes are age appropriate. So for me, a KISS carbine includes some type of Aimpoint red dot optic. An Aimpoint PRO sits on top of my 6720. It’s still an extremely light and well balanced gun. I use Aimpoint T-1 micro’s on my guns at work, but it was hard to pass up the PRO, considering what they sell for during on-line sales over holidays such as Memorial Day.

10

I agree. The entire FSP debate is a non issue for me personally. If others want to debate this post or that base it is ok by me.

I am entirely condfident that the rifle I just got will shoot just fine and run just fine and be accurate enough for my purposes.

It handles and points very well with the DD rear site I mounted (stole from another rifle I had).

I will be 44 this July and an RDS is something that my middle age eyes prefer over irons but I will still site them in and in practice with irons to the best of my ability. Being able to effecively use both an RDS and iron sites is something I personally feel all AR owners should know how to do.

11

What about using an A2 (colt 6520) upper with a F marked sight base. I was thinking I would take .040 of the front sight post

12

You have good taste. Simple, clean, light and effective. My second to last build is almost identical. I just pulled my MOE off and installed a KAC RAS - I’ll probably keep it on there. I’m planning to pick up a B5 SOPMOD-E and then call it good. If my DD rear sight holds true (no reason to think it won’t) it will stay right where it is on this “optics free build”.

13

We also sell 6720’s for $799. :wink:

http://www.gandrtactical.com/cgi-bin/commerce.cgi?preadd=action&key=6720

C4

14

Great deal, Grant!

15

Great deal, Grant!

16

Damn, that is a good deal. I prefer lightweight profile barrels to government profile ones.

17

That is a good deal!

I wish Colt would make this same setup in a midlength. I am not complaining just wishing.

I can’t shoot it this weekend as my father is in the hospital recovering from some major surgery and I prefer to be with him. In fact I am in his room as I write this while he sleeps.

In a few weeks I plan on breaking it in.

18

I picked one of these up about a year ago. Put a TA-33 red horseshoe ACOG on top and a Geissele trigger inside. I like it a LOT.

At $799 I ought to pick up another–just because!

19

Love my 6720. Aimpoint T1, Geissle trigger, BCM Keymod rail, Surefire X300Ultra, & B5 Systems Bravo stock. Makes for a very lightweight system.

20

That is exactly what I want to do with mine.

What size low profile gas block is used for the 6720 small barrel profile?