I was cleaning up a small parts bin in my desk and pulled out these two 7.5X55 blown out cases that I picked up at the range some time back. I had posted it once, where I don�t remember but suffice it to say at the time no one stepped up with even a guess at what someone had stuffed this poor .30 cal round into. I have not been able to figure it out with the evidence shown on the case.

The data is as follows, the case is ballooned to fill a larger chamber. The new neck line is not even all the way around. The case was fired in a larger caliber, there are identical rim dents to suggest a gas operated weapon. The primers are slightly raised just enough to feel and observe. The brass is marked FNM (Mill?)

Here are the dimensions. Neck opening varies (a little egg shaped) .326 to .328. The length from the base to the new neck (smallest and longest) is 2.030 and 2.054. The dent in the rim is deep enough to raise a burr on the edge. The case is not ballooned at the web but it is clear that it has very little taper to the blown out neck. The dia. Ahead of the web. Is .494 and the dia. At the old shoulder is .460 which is 1.71 in. from the base.

I have not been able to find any cartridge this size with my reference material. It is both a mystery and a wonder and I still shake my head when I look at them. They do give me respect for the concept of fire forming. JB

http://www.picturetrail.com/gallery/view?p=999&gid=1431138&uid=618767&members=1

Could be a 8x63 Swedish. the case dimensions are very close. The 8x63 was chambered for machine guns and the m/40 rifle.

What in the wide wide world of sports did those things headspace on?

Okay, I'm with Carnivore - What did they headspace on? Would the extractor have held them firmly enough for the firing pin to have fired the rounds???? Pretty obvious that we have a real case on our hands of someone being a little less than good sense to have fired two of them?
Regards,

Waxman, that could be it. I do not have data on that just that it is the same as our 30/06 necked up. this ballooned cartridge is longer at the start of the shoulder than the 06. Do you have any measurements? JB

The 8x63 has a neck dia. of .356, a shoulder dia. of .456, and a base dia. od ..479. Case length was 2.58 and cartridge lenght was 3.36.. It was loaded with a 219 gr. bullet past the ogive in order to give it the same overall length as the 30-06 so that it could be fired in Browning machine gun action. It was issued to machine gun crews in a bolt action rifle, but was so powerfull that many were fitted with muzle brakes.

My guess is that the 7.5x55 were headspaced off the bullet.

[ 12-08-2002, 03:34: Message edited by: waxman ]

Could those have been military blank rounds? I have seen some blank rounds fired in autos that looked pretty rough when they were "policed-up"...BCB

I'd think they were shot in a 338 Win Mag Browning BAR.

BCB, we can rule out a blank round because without some projectle there would not be anyting to build sufficient pressure to blow out the neck and fireform the brass. Waxman may be on to someting except I have fired 8mm rounds to compare, and the neck of this is much larger. I think that the poor Swiss round must have been held by the extractor or else the round would have flown forward by the firing pin with the small neck and bullet flopping around in the leade. I would think the primer would be more deformed or blown out if it fired loose in the front of the chamber and ballooned backwards to fill the chamber void. JB

I put up two more pictures, one showing the neck opening next to a smaller 8mm neck and another showing the shoulder compared to a fired 8mm and �06. JB
http://www.picturetrail.com/gallery/view?p=999&gid=1431138&uid=618767&members=1

A few things come to mind, like the 8x63 Swedish or the 8x59 Breda for example.
How does it compair to somthing like those?

This reminds me of my trying to make a case into something it was not supposed to be in the first place and also without the benefit of form dies.This is just a wild stab in the dark but it looks like[to me] a case that was run into a sizing die in an attempt to make a larger cartridge. Perhaps the 7.5 necked to .338? Maybe a 7.5/416? Believe me, in 30 years of fooling around trying to make something "different" I have inadvertantly made cases that look similar to the ones in the pictures. Just my .02. Aloha and good luck, Mark[in Or]

WOW! Could it be 8X57 ammo fired in a 8mm06 AI chamber?? !!

It looks to me like a 308 win. I saw once that was fired in an 06 chamber. I would guess it was fired in a 338-06 or a 35 Whelen chamber. What do ya think?

After looking again at the pics, I would say it was a Remington 7400 in 35 Whelen.

[ 01-02-2003, 06:47: Message edited by: ol crip ]