M16 issue - Weapon fires when safety selector switched

[ungawa]

M16 issue - Weapon fires when safety selector switched

I have a lot of experience with M16s. So I have familiarity. On the other hand, I am certainly not an expert on them, and we have experts here on our forum.

This is a Colt stamped M16-A1. Supposed to be original factory machinegun.

I bought an M16, and I expect the NFA transfer to be completed within days from now. When I walked into the dealer's facility, I was all googoly-eyed and a little nervous.

None of the following involved firing the weapon with ammo, simply function tests with an empty weapon. I would cock the firearm and release to battery. When I moved the selector switch, either from Safe to Semi or Safe to Auto, I don't remember which, the weapon would fire. Every time. This concerned me, and I asked my dealer about it, and then I decided it was because I hadn't released to bolt from a locked position into a positive battery using the bolt release - I assumed I released the bolt too slowly. None of my rationalizations at the time make sense now. Understand I was a very high on adrenaline at the time. I cannot get any of my AR-15s to repeat this behavior.

The firearm is guaranteed. This does not help very much because if I want to give it back I need to transfer it back through ATF and find a new one to start over.

So, any diagnosis on this? Has it been too long since I fired an M16 and do they all sound like they fire when switching the selector? Probably not. Any idea what could be wrong with it and what it would take to fix? "Send that stuff back" does not take into account the cost and time of starting over, I may be willing to deal with a simple issue.

[Stack]

Something does sound funky bud - I hate to say it. The internet isn't paying off much on this one either but I have found a couple of statements that, if I am reading your post correctly, lead me to my conclusion (which doesn't mean much!):

Taken from a website with the history of the M16:

The rifle will not fire unless the bolt is locked and the bolt carrier is in its forwardmost position. My A2 was the same way (obviously) Taken from here:
http://world.guns.ru/assault/as18-e.htm


Here is a link to an old TM for the A1 - page 22 describes the function check:

http://www.biggerhammer.net/manuals/...912/TMM16A.PDF

Still trying to find some answers.........

[JayBell]

this is most likely caused by a bad disconnector, or bent sear, or broken trigger.

the sear itself moves position when the gun is switched from semi to auto.

on semi, the top of the sear is switched forward so that the sear is not in a position to be tripped by the bolt carrier when its closed.
in this setting, the hammer catches on the trigger notch, and the disconnector merely prevents the hammer from being released until the trigger resets.

in auto, the top of the sear moves rearward so it can contact the trip area, and the tail of the sear can trip the disconnector to drop the hammer while the trigger is pulled.
In this setting, as long as the trigger is pulled, the hammer catches on the disconnector only, to be released when the carrier trips the sear.

so, at this point, it sounds like the disconnector may not be catching the hook on the hammer right, OR, possibly the trigger is not catching on the hammer notch right, so the disconnector is the only thing holdingt he hammer back.

that means as soon as the selector is switched, and the sear moved, the hammer dropped.

M16 innards are cheap, buy a new hammer/trigger/disconnector set and replace them.

that should fix it.

[ungawa]

Thanks, only makes sense. I should have thought about it logically. It's not like I have anything truly problematic like a registered lower receiver so bent that it doesn't work right.

[PA Rifleman]

If it's releasing the hammer with your finger off the trigger, it has a problem and could discharge without warning. If it's releasing the hammer when you move the safety, it definitely has a problem. If you had the bolt back, the hammer would have been held down by the bolt carrier.

I'm a little surprised the dealer didn't do a pre-delivery check, since a bad sale with a Colt M16A1 would involve tens of thousands refunded. What did the dealer offer as an explanation for this symptom?

I've already replaced several fire control components in my M16A1 already, so it isn't unusual. The good news it's fairly easy to do, although the dealer should make it right before handing it over to you.

In my case, it would fire when the trigger was *released* after pulling, not during the initial pull.

[Stack]

Serious business... I'll take it off your hands for 6K. You have to pay the stamp though - let me know, I'll even pick it up (you don't have to deliver - save you a couple of bucks in gas).

[sluggie24]

Is this a registered reciever gun? If so It should be cheap to fix. You would just have to pick up and install new fire control parts which can usually be purchased as a package. Just have the seller take the cost of them off the price.

[ungawa]

The rifle is fantastic, works perfectly, and it looks even better than I remembered. Don't know if I was imagining things or if the dealer made a repair before I picked it up. I think the former. I did notice that the large "pin" (?) that holds the selector group in the receiver looks pretty new. All other fire control pins look vintage. But the selector knob itself looks vintage. Not sure what it means if anything, and really don't care too much.

I'm sure I used all the wrong terms but I'm not breaking out the diagram and you get the point.