HELP, ar 15 issue....

slind · Oct 21, 2014

hey everyone. had a round that i loaded into my ar 15 from my mag by releasing the bolt and when i ejected it the primer had a nice size ding on it. more than a nick from the firing pin. I recently cleaned it and pulled apart the bolt and parts and put it all back together and it functions fine. but maybe i missed something. should my firing pin be leaving marks on my primer at all. this really suprised me since i have never seen this before...]
any suggestions as to what may be wrong or what i should do. i am afraid to even load one until i am at the range or in the woods and gun is pointed in safe direction. not that it wasnt when i did it but you never know. ...
please help if you have any input thanks.

happypuppy · Oct 21, 2014

The pin floats in the channel and will leave a primer mark on many if not all to some degree.

Examine If the pin moves freely and does not protrude more than it should.

erudne · Oct 22, 2014

you should be able to buy a firing pin protrusion gage
on the other hand if you shoot steel cased ammo, there could be carbon build-up in the chamber that may contribute to your problem, Use a strong flashlight to look into your chamber.

IronMonster · Oct 22, 2014

I dont buy that, If there is enough carbon in the chamber that it would affect where the cartridge seated then the bolt would not be going into battery.

Could you post a pic of the impacted primer? Is it seated all the way in the case? That would be my first thing to inspect was the cartridge, especially if you have fired the rifle considerably without having similar issues.

If you come to the conclusion it is your rifle since you are in Seattle I would recommend taking it in to Rainer Arms in Auburn and explaining the problem to them. They have a AR armorer on staff that has all the proper tools to verify there is not a clearance issue with your bolt/barrel

Mr Smith · Oct 22, 2014

There can typically be a slight ding as the firing pin does free float. but it takes a hard strike to set off a .223/5.56 primer. for safeties sake though, be sure your firing pin is clean and clear of debris, and well lubricated. There are lubrication points in the side of the carrier you can put a drop or two of gun lube down to ensure the firing pin is lubricated.

put a drop or two of gun oil in there, and without a magazine or round in the gun, rack the charging handle several times to help work the oil into the firing pin which will move the bolt in the carrier several times which also moves the firing pin..

You can also remove the bolt/carrier and by hand move the firing pin... it should freely move and not have any stiffness feeling to it.

slind · Oct 25, 2014

this is the round and dent. you can feel the dent with your finger. but i am taking it to the range to text it out and point it in a safe direction and try loading it the way i did when it did this. i have never noticed any dents before. but maybe this is normal. and i would normally not load it in my home.

ZA_Survivalist · Oct 25, 2014

slind said:
this is the round and dent. you can feel the dent with your finger. but i am taking it to the range to text it out and point it in a safe direction and try loading it the way i did when it did this. i have never noticed any dents before. but maybe this is normal. and i would normally not load it in my home.

Yep, looks like a "Primer kiss"
Most of not all free floating firing pins will lightly touch ("kiss") the primer when a round is chambered. I've yet to hear about a negligent discharge (ND) from it.. But it's the reason when I rack a round in the chamber of one of my AKs or ARs I leave it be or rotate it down the mag. Unsure if racking the same round time after time would cause the primer to go off.. But I sure wouldn't want a round flying through the house.

Snap caps work great for that kind of practice and rechambering.