Author: Shamu
Subject: Just scrap.
Posted: 11 February 2014 at 4:56am
Couple of things. Messed up chamber, wildly messed up head space.
The brass factors in as well, take a look at the sectioned cases. See how the thicker, harder rear end is on one side of the canyon & the thinner, softer part is on the other?
What happens is the thinner front end expands & grabs the chamber walls, locking into place til the pressure drops. The rear, being more resistant to expansion stretches rearwards till its jammed up against the bolt face. The point between the 2 sections gets stretched thinner till it fails.
Now look a Muffet's brass it failed just ahead of the solid rear section (base) of the bullet. Thats because the non solid part extends outwards during firing (because of under-sized brass or a too wide chamber) & the solid base can't do do so there is a similar fault but in a different spot.
Subject: Just scrap.
Posted: 11 February 2014 at 4:56am
Couple of things. Messed up chamber, wildly messed up head space.
The brass factors in as well, take a look at the sectioned cases. See how the thicker, harder rear end is on one side of the canyon & the thinner, softer part is on the other?
What happens is the thinner front end expands & grabs the chamber walls, locking into place til the pressure drops. The rear, being more resistant to expansion stretches rearwards till its jammed up against the bolt face. The point between the 2 sections gets stretched thinner till it fails.
Now look a Muffet's brass it failed just ahead of the solid rear section (base) of the bullet. Thats because the non solid part extends outwards during firing (because of under-sized brass or a too wide chamber) & the solid base can't do do so there is a similar fault but in a different spot.