The original thread was getting rather long, so I felt that it might be better to start afresh now some 'pictures' are available.

Below is a TERRIBLE QUALITY photograph of the blown 6mm Remington case that this thread has been all about, and two (2) dimensioned sketches of same.





The case appears in the photo the same way up as it would have lain in the chamber at the time of firing. Though not really visible in the photo, at the top of the case there is a ridge where brass flowed back into the ejector slot in the top lug. The ridge stands approx 0.025� out from the (sort-of) intact part of the rim on the right side of the case. The left side of this ridge drops away into the torn out part of the case head.

The sketches show the most relevant dimensions, which may help to make up for the poor quality of the photo. The length of the case from head to mouth is still the same as the average length of the rest of the lot, 2.225�. The length of 1.76� from the case head to an arbitrary point on the shoulder was obtained by slipping a 0.670� long machined brass sleeve with an internal diameter of 0.390� over the neck and on to the shoulder, and measuring from the case head to the outer end of the sleeve. (then subtracting 0.67 from this measurement, obviously)

This procedure was repeated on several other cases from the same lot, which had been fired three times, and the same dimension was obtained. However, the extraction groove of the damaged case (in the portion which still exists) has closed up quite appreciably, from 0.09� to 0.06�. So both stretching and shortening seem to have occurred in different parts of the case. The depth of the primer pocket, where the case rim and the bottom of the pocket are still intact, has reduced from 0.125� to 0.10�.

I hope this will assist the expert 'case interpreters' in their deliberations.

Red

Hmmm. No images displayed!

The original images are at:

http://www.momentoffame.com/snapshot.html?id=38139

and

http://www.momentoffame.com/snapshot.html?id=38266

I thought I had followed all the instructions about how to display them here, but it obviously hasn't worked. Can anybody help, please?

Red

let's try this.


hope it works!
montero

let's try this.
[img] http://www.momentoffame.com/snapshot.html?id=38139 [/img]
[img] http://www.momentoffame.com/snapshot.html?id=38266 [/img]
hope it works!
montero

I through the towel in!
No one can say I didn't try...
Regards,
montero

redrover---

The straight line of failure through the flash hole ain't natural, in my experience. I've never seen that before and is very suspicious.

I would seriously question the integrity of the brass. I'd also examine the bolt VERY well to be sure there's not a problem with a cracked bolt face that unsupported that side of the case. (I doubt it....they usually break, not crack).

I can't remember ever seeing a blown case head on the side opposite the extractor, either. By design the extractor should break and allow a failure away from the shooter's face. (The military taught southpaws to shoot right handed in the days before the Garand.)

Not much help I know.....the next step would be microscopic examination of the case looking for existing cracks or flaws in the brass.

A detailed look at the fracture surface might give you the answer. The strangest fracture I came across was in a 45acp case . After a careful examination I determined that the male die was poorly made. The brass ,instead of flowing smoothly around the die, was slightly torn. This tear propagated with firings until the case ruptured.

It looks like a lot of ductile metal flow ocurred. I would say some hardness tests are in order.

[ 05-21-2003, 04:37: Message edited by: Vibe ]

Thanks, Vibe.

How did you do it?

Red