Registered auto sear for a 6920

**Ed L.** · 09-02-17, 20:35

Let me start by saying that this is a topic I know nothing about and I am at a place with a very slow internet connection so the search engine is not an option as iit took 5 minutes to log in and get to the screen where I can post this topic

I have someone who might be interested in selling me a registered sear that will make my 6920 gun select fire. I asked him some questions but I would rather post the questions to the board to get a fresh view from a variety of knowledgeable people.

First question, can a registered sear be dropped right into a 6920 by just switching out parts from the fire control group or is the 6920 lower set up in a way to prevent this? (I do not have my 6920 with me to look at). The person who is interested in selling the sear did not know if it could be put in without having to modify the lower.

2. Will the registered auto sear allow semi-auto fire also?

3. I believe the potential seller said that the sear could be switched between ARs without having to have each AR registered with the ATF--since the sear itself is registered. Is this correct?

4. Will the registered sear affect the semi auto trigger pull? I have standard Colt 6920 trigger groups in my 6920 and 6940 and am quite happy with them.

5. Is this registered sear reliable? If I am sacrificing reliability I see no reason to buy it. My intention is to fire the gun mostly in semiauto.

6. Finally, is $20k a fair price for the registered auto sear?

Thanks!

**SteyrAUG** · 09-02-17, 21:33

It depends. All kinds of sears out there of varying quality.

I'm pretty sure 6920s have a blocking bar that would have to be milled out. And if the registered receiver requires the drilling of a sear pin hole than that sear will be married to your receiver. There is no walking it from firearm to firearm because once you drill a sear pin hole you have manufactured a machine gun and ONLY a registered sear keeps it at preban status.

Now if it's a drop in (DIAS) then that's different, doesn't require the receiver to be drilled but I think you still would have to mill out a blocking bar on a 6920 which ATF may consider "modified as a machine gun." You'd be much better off tracking down an older Colt AR-15 which wouldn't need to be modified to accept a DIAS.

But again, lots and lots of variables.

**ccosby** · 09-02-17, 23:43

Yea need to know what type of machinegun it is. For 20 grand I'm guessing it is a lightning link which isn't a good price. If it is a registered drop in auto sear than it is a great price. If it is just a registered normal sear I couldn't tell you.

There is a very good chance the 6920 lower will have to be modified to work with the drop in device. Some other guns lowers are designed to work with them. With any drop in device you might have to do some tweaking to get it to work correctly.

**Iraqgunz** · 09-04-17, 23:08

Most Colts 6920's, etc.. will not be machined to allow an auto-sear to be used. You will also need to purchase a full auto fire control group for use with the automatic sear.

**Ed L.** · 09-04-17, 23:58

Thanks so much, guys. I have nixed the idea of an autosear.

I am still not home and not on my regular computer and struggling with a slow internet connection.

Next question.

If I buy an M16a1, can I use the lower to accommodate an HK416 upper? I mean is the pivot pin different from the newer AR15s and M16s? I would have the receiver extension replaces with a 6 position collapsable one.

**JoshNC** · 09-05-17, 00:37

As others have said, the 6920 (and all White label to current production Colt lowers) will not accept a DIAS without modification. Late 90s to current lowers have a web of metal intact in the autosear pocket and would need to be milled to Colt SP1 spec for the DIAS to fit. There are a few non-Colt lowers that are in spec from the factory for DIAS use. It will be easier/cheaper to just buy one of these and use the autosear in it. A DIAS is mechanically identical to a GI spec autosear (and therefore allows semi and FA fire) with one exception, it catches the autosear engagement surface on the FA hammer during both semiauto and fullauto fire. The GI autosear's hammer engagement surface is cammed away from the hammer by the selector when the selector is set to semiauto. The DIAS cannot be used with a burst mechanism, though I can't think of any reason to use the terrible M16 burst FCG. As an academic aside, the HK automatic sear (both the non-factory "registered" sear and the factory sear) also functions at all times in both semi, burst, and FA.

Any chance you know the manufacturer? That would be helpful. DIAS come in two flavors- aluminum body and steel body and cost $32k to $35k respectively in the current market.

It is also possible that he is calling a lightening link an autosear. A LL uses the factory semiauto FCG and SP1 spec (not FA) bolt carrier. The link paddle is tripped by the carrier, cams the disconnector rearward to release the hammer. A burst FCG and selector can be modified to allow semi and FA function with a LL. The LL is around $12k in the current market.

**JoshNC** · 09-05-17, 00:40

Originally Posted by Ed L.

Thanks so much, guys. I have nixed the idea of an autosear.

I am still not home and not on my regular computer and struggling with a slow internet connection.

Next question.

If I buy an M16a1, can I use the lower to accommodate an HK416 upper? I mean is the pivot pin different from the newer AR15s and M16s? I would have the receiver extension replaces with a 6 position collapsable one.

Hk416 upper to M16A1 fit is plug and play. You just need the 416 spec FA hammer, which is designed to engage the firing pin safety. The 416 spec Geissele SSF is the way to go.

A couple weeks ago I dropped a friend's 416 upper on my m16a1 lower with SSF FCG. It is not the 416 spec SSF and it would not fire because the hammer does not engage the firing pin safety. It was a real blue ball experience for all involved.

**Ed L.** · 09-05-17, 21:55

Originally Posted by JoshNC

Hk416 upper to M16A1 fit is plug and play. You just need the 416 spec FA hammer, which is designed to engage the firing pin safety. The 416 spec Geissele SSF is the way to go.

A couple weeks ago I dropped a friend's 416 upper on my m16a1 lower with SSF FCG. It is not the 416 spec SSF and it would not fire because the hammer does not engage the firing pin safety. It was a real blue ball experience for all involved.

I would thing that an M16 would have a flat faced hammer, unlike those of a 6920 that have a little notch on the top of the face of the hammer--the part that hits the firing pin.

Sorry, I am away from home with slow internet so I can't search the net and post pictures.

Thanks for your help, guys!

**MegademiC** · 09-05-17, 22:33

This link is a pic showing the difference:
https://goo.gl/images/hgwfFu

If you can post a pic of what he is selling, it should help.

LL = thin piece of metal with a lever
RDIAS = block with lever
RR = entire lower.

Why have you put a kibosh on the DIAS?