458 Short mag

[J E Custom]

This is not a "true short mag" in the sense it will function in a short action, but it is a shortened 458 Win mag, but it is a real thumper with 400 or 500 grain bullets.

The purpose of this cartridge was to find/build something that could easily match or exceed the 45/70 Gov in a modern designed cartridge/case in a rimless case. 2,000 to 2250 ft/sec with a 400 grain bullet was the goal. I have loaded 45/70 hard in modern rifles and the cases suffered.

The 458 win mag is a hand full for many shooters, so a shortened version solved this problem. The case is 2.375 instead of 2.500 like the 458 win mag. it will easily top 2,000 ft/sec and can be shot in a 458 win mag but the 458 win mag will not chamber in the 458 short mag. it also lower the chances of a squib load at reduced velocities.

The friend I built it for really likes it and the performance will almost match the 458 win mag if so desired. He prefers to shoot 350 to 400 grain bullets in it and says the recoil is noticeably less than his 458 win mag. he also has a 45/70 and says it is like a 45/70 on steroids, but is very easy on the brass. (Trimmed 458 cases). it has become his favorite hog gun. It also opens up a new batch of powders because of the reduced case volume.

He said than 2000 to 2100 are the range he loads to and likes the combination best. He also uses his standard 458 win mag dies with great success and ease. Muzzle energy is a conservative 4,000 ft/lbs

Just something to fill a niche between the two cartridges.

J E CUSTOM

 

[TXAoudadKlr]

If he's impressed with that he should try the 260gr Maximus in 458 out of it

 

[wdrjr]

This is not a "true short mag" in the sense it will function in a short action, but it is a shortened 458 Win mag, but it is a real thumper with 400 or 500 grain bullets.

The purpose of this cartridge was to find/build something that could easily match or exceed the 45/70 Gov in a modern designed cartridge/case in a rimless case. 2,000 to 2250 ft/sec with a 400 grain bullet was the goal. I have loaded 45/70 hard in modern rifles and the cases suffered.

The 458 win mag is a hand full for many shooters, so a shortened version solved this problem. The case is 2.375 instead of 2.500 like the 458 win mag. it will easily top 2,000 ft/sec and can be shot in a 458 win mag but the 458 win mag will not chamber in the 458 short mag. it also lower the chances of a squib load at reduced velocities.

The friend I built it for really likes it and the performance will almost match the 458 win mag if so desired. He prefers to shoot 350 to 400 grain bullets in it and says the recoil is noticeably less than his 458 win mag. he also has a 45/70 and says it is like a 45/70 on steroids, but is very easy on the brass. (Trimmed 458 cases). it has become his favorite hog gun. It also opens up a new batch of powders because of the reduced case volume.

He said than 2000 to 2100 are the range he loads to and likes the combination best. He also uses his standard 458 win mag dies with great success and ease. Muzzle energy is a conservative 4,000 ft/lbs

Just something to fill a niche between the two cartridges.

J E CUSTOM Is that The 458 American?

 

[wdrjr]

Is that called the 458 American?

 

[J E Custom]

Is that called the 458 American?

No. the 458 American uses a 2.000 inch case and has less case capacity than the 45/70 (case length is 2.105") and the only advantage it has over the 45/70 is case strength design.

We wanted the short mag to start where the 45/70 reach its peak pressure and velocity. the 458 short mag starting low, is the highest the 45/70 Can/should be pushed. It will reach the same velocity as the 458 Win Mag but it is tough on everything and not the purpose of the short mag.

Just another fun design/wildcat.

J E CUSTOM

 

[Possum Cop]

This is not a "true short mag" in the sense it will function in a short action, but it is a shortened 458 Win mag, but it is a real thumper with 400 or 500 grain bullets.

The purpose of this cartridge was to find/build something that could easily match or exceed the 45/70 Gov in a modern designed cartridge/case in a rimless case. 2,000 to 2250 ft/sec with a 400 grain bullet was the goal. I have loaded 45/70 hard in modern rifles and the cases suffered.

The 458 win mag is a hand full for many shooters, so a shortened version solved this problem. The case is 2.375 instead of 2.500 like the 458 win mag. it will easily top 2,000 ft/sec and can be shot in a 458 win mag but the 458 win mag will not chamber in the 458 short mag. it also lower the chances of a squib load at reduced velocities.

The friend I built it for really likes it and the performance will almost match the 458 win mag if so desired. He prefers to shoot 350 to 400 grain bullets in it and says the recoil is noticeably less than his 458 win mag. he also has a 45/70 and says it is like a 45/70 on steroids, but is very easy on the brass. (Trimmed 458 cases). it has become his favorite hog gun. It also opens up a new batch of powders because of the reduced case volume.

He said than 2000 to 2100 are the range he loads to and likes the combination best. He also uses his standard 458 win mag dies with great success and ease. Muzzle energy is a conservative 4,000 ft/lbs

Just something to fill a niche between the two cartridges.

J E CUSTOM

Sounds interesting and looks like a hammer.

 

[TXAoudadKlr]

any changes to the sizing die?

 

[J E Custom]

any changes to the sizing die?

By only cutting the case .125 thousandths, he sizes to the belt with the 458 Win Mag dies and bullet tension is still good with less than .0005 difference it is not enough to be a factor. The only change was to the chamber with the case mouth shortened to 2.375 so the reamer would place the case mouth to the new length and prevent the 458 Win Mag from chambering in the short mag.

Very easy to load with. The same principle as loading the 45 long colt, the 454 Casull and the 460 S&W with the same 460 dies.

J E CUSTOM

 

[J E Custom]

Up date :
several years ago I also built another short mag buy trimming the case length .250 Thousandths, for using the 350 FTX and after checking the records found that the 8 mm rem mag cases would work
By trimming the neck and shoulder to 2. 250 and running them through the 458 Sizing dies, so this added another case to use for the the 458 short mag and the 350 grain bullets kept the pressure down even at 2600 to 2700 ft/sec.

It also allowed the use of older actions that were designed around 45,000 to 50,000 cup/psi.

J E CUSTOM