450-500 Express

3 yrs ago I asked Ray Meketa to help me with this cartridge. I didn’t have the right info for him. The brass is a belted mag. 2.875 OA length. It is a 458 caliber. It is 2.500 from the base to the shoulder. The shoulder diameter is .500 and the diameter above the belt is .510. The 450-500 Express was stamped into the barrel. Any help on this cartridge would be much appreciated.

This is probably a fireformed wildcat derived from the 375 H&H case.

Your case is very similar to several .458" wildcats based on the 375 brass, except for the base to shoulder lenght.

There are the 450 Ackley and the 450 Barnes Supreme that have 2.83" -2.85" case lenghts , 2.36" - 2.37" base to shoulder lenghts and .500" diam shoulders. These are standard dimensions reported by several sources.Note that, being wildcats, these dimensions can vary slightly.

Anyway those case lenghts are reached only in factory made cartridges for example Qual Cart or A-Square. The original 375 H&H case has a lenght of 2.85" and a 458" fireformed wildcat directly derived from that case is shorter ( my 450 Ackley sample, even if made from a fireformed 416 Remington magnum case has a shorter neck than standard drawings).
I suspect that someone used a BASIC belted case ( cylindrical) to form your cartridge. This basic brass is usually 2.85" to 3.00" long

Don’t know what the “500” means, maybe it refers to the bullet weight. This is a typical bullet weight for high powered .458 cartridges and the rifle could have been tuned for use that weight.

Hey Butch, welcome to the best “cartridge” forum on the internet. I’ve been hiding here for a long time.

Pivi is one of our more knowledgable collectors when it comes to wildcats, and I think he has nailed it. My guess would have been the same as his. Unless you can find the guy who “designed” the cartridge, you can only guess what he meant by 450-500 Express. There are several cartridges with similar names and they usually mean a 500 necked down to 450, or a 450 with a 500 grain bullet. If there is no headstamp, he used some of the basic brass from one of many brass manufacturers.

For members that do not know him, Butch is a shooter, gunsmith, collector. One of the good guys.


Ray, thanks but I am still a rookie wildcat collector and I have just started to scratch the surface of this subject…
There are far more experts here… and this means you too !

Thanks Ray and Pivi. I purchased the rifle from a member of the Accurate Reloading forum. He is a standup guy. He had acquired it in trade. I believe the 458 basic brass that I fired through it came from Ray. I did a chamber cast before fireforming a piece of brass. The basic brass is not long enough to form the whole length of the neck. The rifle is a Mod 1917 Enfield. The builders name that is stamped on the barrel is Reed Thompson Jr. I haven’t found anything on him yet.

Standard BASIC belted brass is about 2.385" long.

Anyway Bertram once produced the 458 Express case, that is 3" long, while OPM produces the whole Express line ranging from .375" to .475" based on the same belted 3" case.
Municion.org reports a .475 Ackley sample made by Wolfagang Romey ( so a straight belted case ) with a 2.945" case lenght.
This is a very strange case lenght since these Ackley cartridges ( but also OKH , Barnes and A-Square similar rounds) are still wildcats so they are made from 375 H&H brass or custom made by very few makers, with a much shorter case lenght.
I suspect this could well be another BASIC case example or a special order case.

Anyway, the cases described above could well be modified to form your wildcat obtaining the correct case lenght.