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-   -   Dimpled primer durring charging (http://www.firearmstalk.com/forums/f20/dimpled-primer-durring-charging-76090/)

magnumman 11-10-2012 03:39 PM

Dimpled primer durring charging
 
Typically when I chamber a round in any gun other than a hunting rifle or carry gun, it gets fired. So I was caught off guard when I cleared my m&p 15 at the range for cease fire and noticed that the primer had been struck (lightly). Out of curiosity, I ran about 5 live rounds into and out of battery and all were dimpled. I have an ar but am far from an "ar guy". I know the firing pin floats freely but my gut tells me that this is not supposed to happen. Any input is welcome. Thanks.

msup752 11-10-2012 04:46 PM

That is normal. The free floating firing pin continues forward when the bolt stops and will strike the primer. It is more likely there is something wrong if you don't see the light primer strikes.
If it bothers you, release the bolt and use the charging handle to slowly let it close and a few taps on the forward assist.

CamoToe1 11-10-2012 05:28 PM

I had the same thing last weekend. I thought the round had been dimpled by nearly charging a second round.

When coyote hunting, I ride the bcg forward to be as quiet as possible and then forward assist into Full battery. Somehow I had chambered a round and when double checking the extractor had never grabbed the chambered round. I then attempted to chamber another behind it.... In my defense it's usually pitch black when I walk in. I thought the second round had dimpled the primer, but it was just a previously chambered round with firing pin strike.

Pretty wordy, hope that makes sense.

magnumman 11-10-2012 06:06 PM

Quote:

Originally Posted by msup752
That is normal. The free floating firing pin continues forward when the bolt stops and will strike the primer. It is more likely there is something wrong if you don't see the light primer strikes.
If it bothers you, release the bolt and use the charging handle to slowly let it close and a few taps on the forward assist.

That is what I was hoping to hear. It doesn't bother me as long as it is part of the design. I will continue to slam the bolt home as long as I have no need to worry about sending one down range.

robocop10mm 11-10-2012 09:02 PM

The AR is designed for use with 5.56 mm MILITARY ammo, Machinegun ammo. The military primers are much harder than most commercially available primers. Using commercial .223 ammo you will see the slight dimpling. Rarely does this result in a slamfire (avoid Federal primers as they tend to be the softest).

I have NEVER seen or experienced a slam fire because of this. If it concerns you a bunch, look into a Titanium firing pin. The reduced mass of the Titanium will greatly reduce this tendancy.

magnumman 11-10-2012 09:14 PM

Interesting. Thanks for the info

locutus 11-10-2012 10:23 PM

That's why MilSpec primers are harder and thicker than so-called sporting primers.

All military ball ammo is loaded with these type primers.

Commercially, only Remington 7 1/2 and the special order CCI are MilSpec. These two should be used for handloading if you're loading for a military semi-auto.

hiwall 11-10-2012 11:53 PM

Change to a Ruger Mini-14, problem solved

Quentin 11-11-2012 04:06 PM

Quote:

Originally Posted by hiwall (Post 1009547)
Change to a Ruger Mini-14, problem solved

I'll pass.

Tackleberry1 11-11-2012 04:50 PM

Op, GREAT question!

I've been using the AR platform since 1991 and NEVER noticed this before?

This is why I appreciate FTF! :)

Tack


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