WOW.........How stupid can people be? That's nearly as dangerous and stupid as firing 300 WM in a 375 Ruger................or a 300 H&H in a 300 Wby.....or a 30-06 in a 35 Whelen .....or a 30-40 Krag in a 35 Win....or a 30-30 in a 38-55.............
Or how about this one..........a 308 in a 30-06...that would really be tempting fate.......OH wait...I heard somewhere that it was one of the design criteria of the 308/7.62 Nato, that it be of such a configuration that it headspace and fire in the millions of 30-06 rifles still in use in the military in 1952.....
I would willingly shoot 300 WM from my 300 Wby if I was out of ammo and had a wounded animal to finish, and my buddy or PH had a pocketful of 300 WM. I'm sure it would shoot close enough to POA @ 10-20 mtrs to do the job, and no it is not the slightest bit dangerous, well except out the muzzle end.......
There are many fireforming conversions that are perfectly safe and accepted practice, 30-06 to 35 Whelen, 300 H&H to 300 Wby and so on. Where it gets dangerous is when one tries to drive a larger bullet down a smaller bore without any jump. I saw the remains of a Parker Hale 7mm Rem Mag that attempted to fire a 303 British..........not a recommended conversion. Another I would not try would be a 308 in a 300 SAUM, although it may actually headspace and have the correct diameter bullet I doubt anybody's brass would take that amount of expansion without splitting and releasing a significant amount of gas at high pressure.
I have fireformed many, many cases in my wildcatting days without incident, except possibly losing a few cases. Understanding what the brass will and will not do under pressure it the key, with some common sense added, it can be perfectly safe. I have developed a few rules for forming cases through fireforming. Firstly the forward 1/2 of any rifle case will do pretty much anything you ask of it during fireforming, as long as the base is a close fit to the chamber and the case headspaces close enough to fire. Rimmed and belted cases are the best example of this, you can make 38-55 by fireforming 30-30 or 32 Spl or 32-40 in a 38-55 chamber. All of these cases are of the same family and design and one can make any one from another by fireforming or running through a full length die........without any risk what so ever. It is also safe to fire any belted mag cartridge in a larger belted mag chamber (talking only of the .532" belted cases) as long as the bullet is equal to or smaller than the barrels dimension. One can safely make 300 or 340 Wby by firing 300 H&H in a 300 or 340 Wby chambered rifle. I make all my 300 Wby this way and I make my 340 Wby by necking down 375 H&H until it fits in the chamber and then fireforming.
I have only changed the overall diameter on one case and that was fireforming the 300 Win Mag to 375 Ruger. The case lines up perfectly in the chamber because the belt matches the base dia of the Ruger case and the headspace is pretty much perfect. This allows the entire case body to expand concentrically because the belt is centering the case at the back of the chamber and the cone of the shoulder is centering the case at the front. Other than these two points of contact the case doesn't touch the rifle chamber anywhere else, but these two points are the only critical dimensions that need to be shared between these two cases, all else is open to change. It worked out flawlessly and there is no indication of stress cracking at the belt/body junction which was my only concern in doing this, because the head section of any rifle case is thicker and harder than the forward 1/2 of the case.
Anyway my whole point is not to condone what some idiots are doing through total ignorance, and getting away with it.........it is only to point out that changing case dimensions, even radically, can be done safely through fireforming WHEN ONE KNOWS WHAT THEY ARE DOING !!!!!!!!!!
