in the pic you can plainly see firing pin impressions, this is just from chambering a round and then later ejecting it. this is why they say to not chamber it unless your gonna fire it. or put it in a box for the target range. what happens is since there is an impression in the primer ignition doesnt acure like it is suppossed to. thats what is being said anyways, makes sense to me. that enough should be a good reason to keep your bcg and firing pin clean
This is normal for an AR15.
Don’t worry about it, it would only be a problem if your repeatedly chambered the same round over and over again.
Cameron
This is normal with an AR and free floating firing pin. The real title of this should be “Do not chamber the same round over and over”. The military guidance is that it should be done no more than 5 times (IIRC).
Momentum of BCG slamming the round home, carries the floating firing pin forward to tickle the primer. Very common.
wow as i reread the post it is titled wrong. geez im sorry fellas i really need to brush up on my writting skills.
Actually, I would be more worried about teh projectile being pushed back into the case, causing issues.
Awhile back, there was a KB in the complex, that was traced directly back to a .40 round that had been chambered numerous times.
Bob
Man and I thought I was going to read a review on a new DDM4V3, V4, or V5. . . 
I became less worried about this after I intentionally set back dozens of rounds of .40 - first just .010", then much, much farther - and fired them through a G22 (in a vise) without issue.
Watched a G22 KB after bullet setback at our dept. Something I still watch for and I don’t rechamber rounds in my handguns or rifles. Old habits die hard.
Every time I think about the FF firing pin and indentations on primers after chambering I think of this post (from this thread: https://www.m4carbine.net/showthread.php?t=33805 might be useful to skim through).
While there are numerous F’ed up things about working in the complex,most a result of it being run by scientists, one benefit, sorta, is they do not believe in accidents.
When something like a KB occurs, they will find out what happended and find a way to prevent it.
You should see what I went thru after injuring a knee on the O course, or taking some frag to the face while breaching a door.
IIRC, the pro-force at the particular facility, was shooting up the duty ammo that is required to be rotated out, once or twice a year, I forget which. Most places use a “barney” bullet, that gets chambered over and over again, they inspected the remainder of the ammo, found the setback, and determined it was the cause.
Bob
I’m certain that it has caused problems.
And I do rotate my carry ammo.
I was just curious about when 180gr Gold Dots would cause a KB. I didn’t find that point.
my policy has been chamber once before rotating down… but i’ve recently started easing the bolt closed and using the FA to lock up.
if that dimpled round hangs around long enough and is chambered enough times it might not even go boom either.
It was after my conversations with Doc after that incident that I started to religiously focus on not rechambering carry ammo. After a round has been chambered it goes into the training ammo can and gets shot up at some point the next range session. It’s only ammo. What’s your life worth?
FWIW I have yet to have a FTF on a chambered round from the training ammo but I just don’t chance it. Not on my social guns.
From PS magazine a while ago (2004). As per the Doc’s advice, for duty use it’s probably safer not to use rechambered rounds altogether.
