.257 B.B. Magnum?

[jpr9954]

I stumbled across an interesting wildcat while perusing a gun auction listing. It is the .257 B.B. Magnum. According to the auction listing, it is a .257 bullet in a necked down .300 Win Mag brass. Given that, it should be a screamer.

I have searched for more info but I've not found anything. It is just a guess but I think the B.B. might stand for "big bore".

Has anyone ever run across this wildcat cartridge? Any idea about loads?

I may bid on this rifle just because. Fortunately, it does come with custom reloading dies.

 

[witchhunter]

My guess is that B.B. stands foe Barrel Burner!

 

[jpr9954]

My guess is that B.B. stands foe Barrel Burner!

That, too!

 

[.308 Norma]

Yeppers, probably Barrel Burner. But no worse, or better (depending on how you look at it) than a standard .257 Weatherby - another necked down, Belted Bottleneck Magnum.