Ammo is '23 factory Igman 55gr 5.56 M193.
Round was failure to fire, did a slap-rack-bang, but no 'bang', just another 'click' w/a resultant double-feed.
Yanked the mag & double-feed out, bolt wouldn't fully close, had to use a cleaning rod to tap out the recalcitrant round.
Examined the recalcitrant round and discovered something I've never seen in several decades of shooting:

Attached File


Anyone got a plausible explanation as to why the primer is extruded w/a firing pin mark *after* the attempted firing? (There is powder in the casing and the extractor did tear the rim off the recalcitrant round)
It couldn't have been extruded prior to attempted firing or the bolt couldn't have locked up enough to drop the hammer in the first place.

Defective case with no flash hole. Pull the projectile and check

Check the flash hole in the case, is it plugged/blocked/missing? The primer going off is an explosion, and if the gases don't have somewhere to go they will force themselves out past the primer, expanding the case head to do this.

Primers do extend from the case during firing, and typically are pushed back in by the case expanding and moving back against the bolt under the pressure of the hot gases.
Garand's original design for the Army semi-auto rifle used this to power the action. Then in 1924? the army started staking the primers and he had to change his design. A recent issue of the Rifleman had an article about the M1 Garand and the competition from other designers, like Pederson.

Yep, that was it!

That's pretty wild for factory ammo.
I've never experienced that.

I have seen no flash hole in both pistol and rifle ammo.

Also seen upside down primers, upside down bullets, etc.

No flash hole was my first thought when I read the initial post.

It happens even to the best of them. I've had ammo from big brand names with this problem as well as finding backwards primers, bullets and other oddities. That's why I always inspect every box and bulk purchases. In your case OP there's no way to detect the defect until you go shooting. Good thing it was at the range and not a life and death situation.