Rapid unscheduled disassembly

[janfred]

This weekend some one brought in a bag of bits including a bolt-locked barrelled action and wooden pieces.

The gentleman in question just returned from taking the first shot with a rifle he wanted to buy using the owner's supplied ammunition. The ammunition was PMP factory rounds for the rifle purchased approximately 25 years ago.

He only had a small scratch on his upper arm and his friend had a black mark on the palm of his hand. The RUD happened on the first shot.

We forced the bolt open using the butstock as a wooden mallet. As expected this broke the extractor. Then the flettened primer, part of the bolt and part of the firing pin fell out as well. A light tap with a cleaning rod down the tube and the case came out as well.

Unsurprisingly the barrel and action was clear and did not seem to have any damage, dings or bulges. The bolt was not so lucky. The extractor was broken, part of the lip around the bolt head was sheared off, the ejector slot was jammed with extruded brass. Bolt lugs looked OK, but needs a proper inspection from a gunsmith.

At first we thought thereust have been a barrel obstruction, but the barrel was clear with no bulges. Then maybe the bullets were reloaded with pistol powder or maybe fast powder like S335 using S365 charge weight. Then we noticed that the neck and half the shoulder of the case is missing.

It was a 7mm Remington Magnum older than 20 years. And the ammo was older than 20 years as well.

My working theory now is that somehow the bullet was welded to the neck and the overpressure is from the neck and shoulder being dragged into the barrel.

[big5ifty]

Good to know there were no irreversible injuries.

Bullet weld is real.

I was once given a number of old 30-06 rounds, of unknown vintage. I immediately pulled them all. The bullet weld on some of them took a lot of force to overcome using a cam-lock puller on a single stage, the verdigris had etched into the bullet shank as well as the case neck.

If there is any more of that ammo, let them bring it to you and pull the rounds, so it doesn't happen to someone else later.