Marked primers

[Howa4AU]

When my rifle goes into battery the firing pin is leaving a mark on the primer. It is a 6.5 CM DPMS variant. Is the buffer spring too stiff? Is the headspace at the edge of being incorrect?

The gun is firing fine with no malfunctions otherwise.

 

[ShtrRdy]

Re: Marked primers

I think this is normal. The firing pin on the AR platform does not have a return spring. Therefore each time the bolt goes forward, the firing pin will "tap" the primer.

 

[poke5353]

Re: Marked primers

Sounds normal bc it is a floating firing pin like standard ar-15.

 

[BCP]

Re: Marked primers

Normal just don't practice chamber the same dented-primer round many times or you might get a surprise...

 

[Howa4AU]

Re: Marked primers

Thanks guys. I have really only noticed one other AR i have that does this. Maybe the others do also- I will have to check. Both of the ones that do have adjustable gas blocks. Don't know if there is any correlation there.

I was just wondering if the buffer spring was lighter or the buffer heavier would it cause less forward drive on the firing pin.

This is my first AR10 type build and these things are much beefier than the AR 15's I am accustomed to . This bolt and spring is stiff and slams shut hard.

 

[NYresq]

Re: Marked primers

All AR's without a firing pin spring will do this, not a big deal, just a side effect of the free floating firing pin. Just dont chamber a round 10 times and it won't be a problem.

If you are really paranoid about it, you can get a titanium firing pin which has less mass and barely leaves a scratch in the primer when a round chambers. I tried one in a DMR rifle I have and it works great, not much more then a scratch, not even a dimple on a chambered round. It is also supposed to reduce lock time because of less weight.

I got it from a friend for free, otherwise I wouldn't have bothered to pay the extra money for it.

 

[Howa4AU]

Re: Marked primers

Where can you find one for a DPMS style 308?

 

[leadbullet]

Re: Marked primers

SNAFU, perfectly normal.

 

[bobbyfairbanks]

Re: Marked primers

It will make you nervous the first time you see that. It happens and a lot of guys after a fews weeks change out the round with dimple on do to them being scared it will not fire. Not sure why but, there is more goofy things that can be done.

 

[leadbullet]

Re: Marked primers

a police officer friend of mine told me that it is department policy to save chambered and unfired rounds and to save them for range only practice, Apparently it has been documented that sometimes the little primer "waffer" can break into pieces if chambered several times and therefore won't ignite the round which would be bad for a number of reasons.
basically, if you eject a loaded round, if it has the little dimple on the primer, shoot it first on the next range trip
hope this helps.