August 11th, 2016

Danger of Defective Primers — Primer Pocket Blow-Through

Primer Blown Gas defect winchester casehead

Think you can “get by” without protective eyewear? This story provides yet another example of why you should wear safety glasses every time you go shooting. You only have one set of eyes — they are much too precious to risk.”

Bad Primer Blasts Gas Through Side of Casehead
Our friend Grant Guess recently had a “close encounter” with a bad primer. An apparently defective primer caused part of the casehead on one of his rounds to blow out. This, in turn, allowed high pressure gas to vent through the damaged primer pocket. Take a good look, boys and girls. This is yet another very good reason to wear safety glasses. The cartridge was a 6.5-06, hand-loaded in necked-down Winchester-headstamp .270 Win brass. Grant reports:

“I had a blow-through between the primer and the primer pocket today. The action was really smoking and I got a face full of gas. This was a reasonably light charge. Thank God for safety glasses.

I should also mention that it appears there is a 3/64 hole that is halfway between the primer and the primer pocket. Like it burned a small jet hole through both of them.”

Could this happen to you? It just might. On seeing this damaged case, one of Grant’s Facebook friends, Chris D., observed: “Search the internet, you will see a lot of these pin hole ‘in the corner’ failures. Obviously Winchester has some issues with the LR primers.”

Careful Examination Reveals Apparent Primer Defect
After this incident, Grant examined the damaged case: “I pinned the flash hole and it is not over-sized or under-sized. The primer clearly has an area where it had a defect. At [50,000 CUP], it doesn’t take much of a defect to cause issues. There was a slight bit of pucker-factor on the next shot….”

Primer Blown Gas defect winchester casehead

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