Why Crimped Primers?

[fredhorace77]

While processing some 223 LC brass today, I got to thinking....why are the primers crimped in. I understand why some ammo may have crimped bullets by why crimp the primer.

 

[Scott Harris]

safety, function in automatic weapons. Google is your friend.

 

[Toolbreaker]

Contingency, I'm guessing. Considering the harsh environments that the ammo has to endure (handling, recoil, machine guns, ect.) the military wants insurance that the components stay together. Brass is considered one-use only by the military, so this makes sense.

 

[fredhorace77]

safety, function in automatic weapons. Google is your friend.

I tried Google and found about 6 million opinions....no facts.

 

[riflewoman]

In many of the early machine guns the barrels were adjustable for headspace. This caused primers to back out and jam the gun. The 30 and 50 cal Brownings could have it happen. When the primers were crimped, the primer actuated Garand became unworkable.

 

[Laurie]

Yes, riflewoman has it. Many military full-auto weapons function with excess headspace settings that would make any self-respecting precision rifle gunsmith recoil with horror. A classic symptom of excessive headspace is backed out primers - put a gap between the bolt-face and case-head and the primer is left unsupported and its detonation pushes it out of the case until it reaches the bolt-face as a stop. Machineguns still function even when headspace is such that cases separate. A classic MG training drill was to deliberately set the gun up badly to subsequently induce a case separation related jam leaving the trainee to clear it, do a field strip, reassemble the gun with correct headspace and resume firing. This might be in a night firing exercise to make things more fun!

In any event, any milspec ammo which might be used in full-auto weapons usually has a crimped in primer in the specification to stop any primer movement out of the case. Purely a reliability issue.

 

[sbhooper]

I have had to fix a lot of Hornady match cases that were crimped. That makes very little sense to me.

 

[rogn]

In the more prevalent consumer day, aswellas, infantry day, the AR action will drop a primer into the works which causes the trigger to malfunction in whatever manner it chooses to. My one event caused the trigger to jam in a nonfire mode which required a complete rear down of trigger mech. Presumably it could also cause the AR to burn the entire magazine at one pull. Yes reliability.

 

[hogan]

debris in chamber COULD cause blown primer if not crimped... lots of other chamber length problems might arise on issued military weapons. Why the hell do they still use a Field Gauge? There's trouble...

So, they're specified to be crimped to prevent one more factor that might cause rifle stoppage in a fight.

 

[amlevin]

I have had to fix a lot of Hornady match cases that were crimped. That makes very little sense to me.

Unless you are the guy shooting those hornady cases in a semi-auto rifle like an M1A/M14.


You really aren't "fixing" them as there's nothing wrong, you are just removing the crimps so you can re-prime.

Don't worry, you only have to do it once.

 

[Bayou]

safety, function in automatic weapons. Google is your friend.

Esp in generously chambered military machine guns.......

 

[DeadEyeDick45]

Simply a milspec feature.

 

[fredhorace77]

Appreciate all of the replies. Thanks for educating me.