Looking for internal photos of true M4A1 lower receiver

AR/M4 AR General Discussion
1

I’m having a good time with my new Colt LE6920 and was wondering what a true M4A1 lower reciever looks like from the inside.

Can you direct me to some high res photos?

2

Give me a second and I will snap you a picture.

3

The same as your 6920 except for the auto sear and FCG.

4

There must be some kind of taboo about posting pictures of FA internal parts, cause I’m having a real tough time finding any. Well I did find a drop in auto sear, but I was curious at what a real M4A1 looked like

http://www.quarterbore.com/nfa/dias.html

This thread certainly had a lot of useful information, but no lower internal parts photos

http://www.ar15.com/forums/topic.html?b=3&f=123&t=296919

It’s cool to see most of the M4A1 mods and markings on the LE6920

5

Nothing taboo about it. Here ya go. Sorry took a bit, had to put the kids to bed.

6

You are the man!

Those are the exact angles I was looking for.

Thank you so much. Are you an LEO?

7

Question:

Am I to understand that the 6920 is cut to the same dimensions as an M4A1 with the exception of the sear pin hole?

Do you know what other lowers are cut this way?

8

My Colt lowers have a “web” where the sear would go…Colt does things like this to prevent people from simply drilling a 3rd hole for a sear. They used to have a big pin sear block but switched to the machined in web.

9

Here is a photo of my LE6920, S/N LE691xx

10

Thats the way My Colt Match target M4 carbine mark Lower is .you can have it Machined out by ADCO for a RDIAS to be used.as long as all the Paperwork is in order

11

I see what you are saying. I’ll be 100% honest I didn’t know that they were doing their lowers that way. All of my lowers do not have that sillyness and I assumed that the 6920 was the same.

12

And in case you were wondering what a lower with burst looks like…

Kind of crowded with the roller or whatever and 2 disconnectors.
Does anyone have a pic of a 4 position lower?
Dustin

13

m16 receivers would also have those cut out.

14

Dustin, the part you are calling a “roller” is actually called the Burst Cam. A 4 position lower would look just like your burst lower only the second disconnector would have a tail that goes under the selector just like the primary disconnector. The selector would also have a little more machining on it to work with the disconnectors.

Here are some photos of the Colt 4-way parts vs. M16 A2 burst parts (the hammer and trigger are the same).

Selector (A2 on the left, 4-Way on the right)

Sear (A2 on the left, 4-Way on the right)

Disconnectors (A2 on the left, 4-Way on the right)

15

Does the 6933 11.5" factory SBR have this configuration too?

Thanks :slight_smile:

/edit I’m considering buying a DIAS at some point in the next 5 years and I’d like to be able to actually “drop it in”, for the curious.

16

This turned out to be such a good picture thread, I wanted to add the Drop In Auto Sear photos I found at http://www.quarterbore.com/nfa/dias.html