Yesterday at the firing range I experienced my first failure to fire that I have ever had with a handloaded cartridge (over 20k handloaded cartridges, all types, fired so far).

The cartridge was one of my, .223 Rem w/Hornady 55 and a Rem 7 ½ BR primer; rifle, AR carbine.

Seemed to be a light primer strike.
(Tried to shoot it twice to make sure.)

I took the cartridge home and measured my primer seating depth.  It measured (avg. of three measurements) at, .009”.   Recommended seating depth is .003” to .007”.

I haven’t taken the cartridge apart so I don’t know if the case has a pocket that’s too deep or whether the primer cup is short and got seated too deep.
For .223 Rem, I always uniform all the primer pockets in my brass because I hate high primers.

One of the more frustrating things about this is that because my ARs are so darn reliable, and because the ammo I make is so reliable, I never practice any form of malfunction drill.  So yesterday I couldn’t figure out what to do right away.  Instead of tapping the mag and raking the charging handle, I first dropped the mag, then pulled the charging handle.

I’m “trained” to do this way, because the only failures I have ever had involve closing the bolt on a loaded mag……with a damn chamber flag still in the chamber!!!   Grrrrrrrr.

It was more than likely a bad primer. It does happen.

I used to be able to say the same thing.  Reloading almost 40 years, thousands of rounds of rifle/pistol ammo and not a single failure to fire.

Then, a year or so back, my nephew had two failures to fire on the same range trip with .223 ammo loaded with Tula primers and IMR4198 powder with 55 grain Hornady bullets.

I tried those two rounds in my AR15 and they wouldn't go off.

Now, only range ammo gets loaded with Tula primers.  The stuff that gets packed away is loaded with CCI or Federal small rifle primers.

As the man said, bad primers, it happens.

I agree, I had a box of Winchester primers years ago that had several primers with out an anvil. I had never seen it before and haven’t seen it since.

Give it a good inspection

Headspace short?
Deep primer?
Dismantle round
Was there powder in there?  A good crimp and no powder sometimes doesn’t even dislodge the bullet.
Is there powder but now it’s all clumped up?
Carefully press out the primer
Is the anvil missing?
Is there an anvil and no kernel?
Did the primer burn? They are smoky when lit but no powder in the case.  In fact I have seen sooty bullet bases from no powder rounds that I pulled apart.
Is there an obstruction in the flash hole?  Like pins or walnut media.

IT happens OP, really, it does you can maybe find out why and maybe you cant.

Check your firing pin extrusion from bolt face, google to find the spec's, anvil in the primer, hammer spring? Headspace?

If all these checkout=s--- happens.

.009'' sounds pretty deep to seat a primer.

Pull it apart and check the primer and pocket, you may have gone too deep with uniforming or the primer itself is short or otherwise defective.

Thanks for the replies.
The above is my first thought.

But I DO own a firing pin gauge and will check that.
And in addition, I will pull the bullet and get that primer out for an exam.  
I'm certain the case has powder in it.  I'm a single stage reloader and I gang my charged cases on a block and always give them all a visual inspection under the work light to guarantee that each one matches its neighbors.

Over the weekend I did a thorough exam and found some interesting things.
So, maybe some of this will be interesting to the forum.

I disassembled the cartridge and discovered that the primer pocket in the Winchester casing I used matched exactly with all the other primer pockets in all the other casings in that box of 50 (.121”).  This isn’t much of a surprise as I uniform all my .223 Rem. brass.

However, the casing was new unfired brass and this stuff measures out in my RCBS Precision Mic at minus .005”.  This is a bit undersized.

The Remington 7 ½ BR primer also measured out as normal; cup depth .112” which is approx. what they will measure once the anvil legs are tensioned.  Unseated anvil legs will be very slightly proud of the cup.  An unseated primer of this type will measure out at .122”.

I think that my .009” recess primer depth was a bit too much, and the result of my being a little bit heavy handed with my priming tool….my bad.

Now things get more interesting.

I field stripped my AR and got out my firing pin gauge.  Using the “maximum depth” end of my gauge against the bolt face with the firing pin pressed firmly in the bolt, I could feel no wiggle at the hammer end of the pin; so far, so good.
BUT, using the “minimum depth” end of my gauge and repeating the test, I got no wiggle again!

The firing pin was not in spec for minimum protrusion from the bolt face.

Fortunately, I keep a spare firing pin in my parts kit and repeated the test with the spare pin.  This time I was able to feel a tiny bit of movement of the firing pin when I conducted a “minimum depth” test.

For those who might be interested, the rifle in question is a new build.  I call it my “Cinco de Mayo” carbine because I built it on the day my town celebrated that holiday.  At any rate, I installed a nickel boron coated bolt carrier group from Texas Brassworks and apparently they sent me a carrier group with an out of spec firing pin.

It seems that everything (firing pin, primer, cartridge case) was close enough that it took a combination of factors before I finally had a failure to fire with this rifle (825 rounds).

Conclusions:

1) I plead guilty to being a bit ham fisted with my priming on at least one primer
2) The firing pin was out of spec.
3) Where was the minus .005” Winchester brass case head spacing?  Probably not on the shoulder, more likely on the extractor, which placed the case head and the .009” recessed primer, “Who knows where, exactly?”