Just Had Quite The Scare. 2 Primers Detonated While Hand Priming.

[Nightvisionary]

In over 20 years of reloading I have never had this happen. I was priming 5.56 mixed cases to replenish my training stocks. CCI is my standard primer but I decided to use up some of my Remington 7 1/2 primers that I stocked up on some time after the Sandy Hook panic. They have been stored in a metal box in my workshop since I purchased them sometime between 2013 and 2015.

I use a Hornady hand priming tool that has primed well over 10K rounds without issue. Just yesterday I primed 100 9mm cases with Federal primers with no issue. Tonight I had one detonate during seating. Luckily I was wearing glasses and the case mouth was pointed away from me so I just suffered ringing in my ears and some carbon marks on my fingers. I inspected the case and found the primer fully seated and no marks on the primer to indicate it had been crushed or damaged. I inspected the priming tool and found no burrs on the seating rod or debris.

I chambered four primed cases in an AR and let the bolt forward forcefully. All four showed the typical small dimple from the firing pin but none detonated. Towards the end of the 100 I had a second primer detonate. I inspected both primers under a magnifying glass and observed very minor flattening from the seating rod but I compared this with other cases and many exhibited the same tool impression. I have also seen this minor flattening many times with CCI and Winchester primers but never had a detonation. Any ideas as to why this happened?

[Krazykarl]

How did you remove the crimp? Swaged or reamed?

[matemike]

That is odd...20+ years and 10's of thousands of rounds and no issue. Blame it on 2020?

Nah. I've had primers get completely crushed because I did not remove a crimp well enough, but they didn't detonate. I've had a very rare double feed in my RCBS hand priming tool where two primers were crushed, but neither detonated. And once I had the rod in backwards so the flat end was down and curved end was pushing the primer. It con-caved a primer so bad that a firing pin wouldn't even make contact, but did not detonate.

I always press the primers in nice and slow. Are you really rapping the handle and slamming the primers in there quickly? That's really the only way I know how to make a primer detonate; is to pop it really good. A force of slow and smooth steady pressure should not make it go boom.

[sinister]

How did you remove the crimp? Swaged or reamed?

That would be my first guess -- the crimp wasn't completely swaged or reamed, the primer caught on the rim, and when the ram finally pushed the primer in it hit the bottom of the primer pocket with enough shock that the primer did its job.

Happened to me with a GI Lake City 5.56 case with a Lee Auto Prime. Don't remember what primer it was, but it was loud.

[markm]

Weird. As pointed out, primers can take a good crushing and not ignite. Some sort of impact is required.

I had one mash in my single stage seating cup, and out of habit, I whipped the priming arm down to clear the cup and when it smacked the press body... Bang!

I run the Sinclair hand priming tool and haven't had an ignition even on some borderline removed crimps where I have to muscle the primer in.

[Nightvisionary]

How did you remove the crimp? Swaged or reamed?

Reamed. If you see on the first pic the prepped brass is in the 5 gallon bucket and about 1/3 full. It is what remains of two full to the brim 5 gallon buckets of prepped brass for my recent projects over the last 18 months. I have primed over 7K mixed 5.56 just from these buckets but, I have exclusively used CCI 41, 450, 400 and a few Winchester primers. There were a few primers that were damaged during seating from crimps that needed another pass with the reaming tool and got tossed aside,even a few that were seated backwards, sideways, and doubles but never a single detonation.

Im leaning towards it being a primer issue or wear issues with my priming tool. I will prime some cases with CCI, Federal, and Winchesters primers. If there are no detonations that should point to a primer issue.

[Jsp10477]

76A3053E-DAEA-4FC7-8760-A6B63A911471.jpeg

I use a lot of 7 1/2’s and never had any explode. I remember reading this about the Lee Auto Prime tool. 7 1/2’s aren’t on the list and considered “unsafe”?

[Nightvisionary]

I just finished priming 100 CCI 400's and 100 Federal 205's. Some of the Federals were extremely tight fitting and required a lot of effort, but not a single detonation out of the 200. This points to an issue with the Remington 7 1/2 primer. The sad thing is I went through my primer boxes and I have 2300 of these suckers left. I just sent an email off to Remington customer service so I will see what happens.

[dmsdog]

I knew an individual that was priming 556 mil cases, probably improperly swaged, with a Lee AutoPrime and had 100 small rifle primers go off in the tray.

of course he was drunk at the time and the next day he looked like he had the measles … fortunate for him that none hit him in the eyes...

[Nightvisionary]

I knew an individual that was priming 556 mil cases, probably improperly swaged, with a Lee AutoPrime and had 100 small rifle primers go off in the tray.

of course he was drunk at the time and the next day he looked like he had the measles … fortunate for him that none hit him in the eyes...

So he was priming without the tray cover in place? That story doesn't make sense.

I primed another 100 CCI 450's last night with no issue so the problem seems to be limited to the Rem 7 1/2's.