Anybody have info on it? I fireformed a 458 Lott piece of brass in it. As close as I can tell, it may be the same as a 450 Ackley Magnum.

The 450-400 is a .40 caliber and brass is readily available; made by Hornady.

I guess I have something else then as mine is 458. The barrel is marked 450-400 Express.

I believe it was usual for British reformed cartridges to list the original caliber first, then the new one-opposite the US naming style.

If invented there, we would have the 06-25 and the 250-22.

Bruce

Butch, so the rifle's chamber was larger than a 458 Lott, I take it? Sounds like the bore is 45 caliber? Maybe a 404 Jeffery blown out to 458, like a 460 Guns & Ammo? A 450 Ackley is a 375 H&H blown out to 458. I had one in a Griffin & Howe at one time. Great caliber, as you can shoot 458 Win, Lott, Watts, or Ackley ammunition in it.

It was the M17 that I purchased from you. I loaded a piece of Lott brass with a 45 cal. lead bullet. I did a chamber cast first. I do need to find the fireformed brass and post the measurements. It is pleasant to shoot.

That's a 500-450, isn't it?

Sir,
It is marked 450-500 Express. Glad I checked it again. The brass is approx. 2.800 in length, 2.500 to the shoulder, .500 diameter at the shoulder and .510 just above the belt. Being as I fire formed basic Norma mag brass the chamber could be a little longer in length. I haven't found my chamber cast yet. I did double check the bore and it is definitely 458

Just found the chamber cast. It is 2.875 in total length.

So 450 is the caliber. 500 is the bullet in grains and express is just cooler than saying magnum. 458 lot improved.