AR15 double fire

[emmie]

was test fireing a AR parts rifle,that I got at a show sat. luckey I use 1rd,2rd,etc method to test with,as rifle double fired at 2rds loaded. with 3rd loaded,it doubles and chambers the 3rd round.
this being my first AR,this was not a happy feeling. what do i need to look at,change out,before the knock on the door?

thank you -emmie

 

[gamachinist]

Hi emmie,
Since this is a parts gun,
have you checked to be sure all the fire control parts are installed correctly?
First thing I would look at it the trigger return spring,and look to be sure the coil spring is even installed in the disconnetor.For that matter,is the disconnetor even there?
Someone may have been trying to make a f/a gun out of it by leaving those parts out,or simply may have lost that little spring or not bothered to find out where it went!
If it isn't something this simple,my limited expierence won't help you without the gun in front of me!
Regards,Robert.

 

[Al Thompson]

IMHO, you'll need to get someone to look it over. I installed a Jewell on my AR and a friends young daughter got it to double almost on demand. Setting the weight a bit higher cured the problem. It may be as simple as that or you may need some new parts. Inspection would seem to be the answer.

 

[simmonsguns]

it sounds like a disconector problem,don't know how much you know about what the factory parts are suposed to look like but,if the disconector hook is rounded off or has been worked on it is better to replace it.military standard parts are a good thing,if the parts have been fiddeled with and you have the money it is better to replace the disconector,trigger and hammer and all springs,start with all new fire control parts,don't settle for someone elses mess.parts replacement will save you the added stress of trying to make do with what you have.

 

[gamachinist]

One other thing I forgot to mention earlier,
It might be slam firing the second round,from a bent,stuck, or too long firing pin.
Who knows what to expect in a case like this(someone elses parts gun).
Check to see that the firing pin moves freely,and rotate it to see if the end looks bent(this could cause it not to retract).
You will need some form of gauge or measuring tool to check the protrousion,a depth mike could be used if you have one and don't have a regular gauge.
I have made gauges for shotguns,by fileing and measuring a notch in a piece of flat metal,you could do the same.
I don't have the spec in front of me,but if you think this is the problem,ask and I'll look it up for you.
Regards,Robert.