Have Never Seen This Before...?

[STORMINORMAN]

Am reloading some 300 Remington Ultra Mag for a friend. His once-fired brass presents no problems. Was looking through the collection of various and sundry brass samples I've accumulated over the years and found a brass case headstamped as " R•P 300 REM ULTRA MAG " . In good shape.

Only thing is this case mouth measures 3.600"(!) and looked so weird next to other fired cases that I hesitated to even attempt to resize it? (Don't need it: have sufficient numbers for anticipated future uses.)

Does anyone know what possible caliber this brass might have been reformed for? A "Wildcat" of some type?

Cheers!

 

[Sevens]

I would think it is much more likely that someone loaded and discharged this round in the wrong rifle and it fireformed rather than this being a piece of intentionally converted or wildcatted brass.

I say this simply because anyone who has gone to the care and trouble to convert brass to something else is VERY unlikely to lose one of his pieces of brass, and a cartridge like this is most likely from a bolt action rifle where it is easy to ensure you have your brass (as opposed to some autoloader that chucks brass to hell & back.)

 

[cmj8591]

How about .358 Ultra Mag Towsley (UMT)? It is a 300RUM necked up to .358 with no other changes to the case. You might find more info if you have a copy of Cartridges Of The World. I don't have access to mine right now but will see if it made the last version when I get back to home base.

 

[STORMINORMAN]

Thanks so much! The fired case was 3.600": guess I should have thought about a bit of expansion at the neck and also looked at .358"...? Although I had never heard of this caliber previously, my research came up with an article in Gun Digest by the creator, Bryce Towsley, dated March 2, 2018. Will measure to see if the fired case length is anywhere near his 2.820" trim length.

The interesting thing is I can't really date the time when I found this brass: I know it has to be way pre-Covid, and was in a group of 75 or so cases of obviously many different calibers left at the range that I picked up.

The other concept might be exactly for what creatures a mere factory Hornady 220gr XLD-X in 300 RUM (2,910 fps @ 4K ft. lbs.!) wouldn't suffice...? That's as far as the North American Continent is concerned: especially on this the Olympic Peninsula? Is Bigfoot really that tough?

There also might have been an actual, possible pachyderm predator in these parts with a trip to the Dark Continent in mind!

Thanks, again!

Cheers!