[csmkersh]

CP,

I just got through reading your article in the Rifleman. It got me to wondering about a load I used back in the 1960s. It was based on a 158 grain 3/4 JSWHP I swedged on a Herter's press. I loaded 12½ grains of 2400 into Remington once fired .38 Special wad cutter brass. My Lyman's manual showed it to be a max .38 Special load and a bottom end .357 load.. Now, 40 years later, my manuals show it to be an over the limit .357 load.

Sooo, have they changed the formulation of 2400 that much or has pressure monitoring improved or lawyering caused them to lower the max loads that much?

 

[Charlie Petty]

Probably a little of all three, but the biggest by far is due to the differences in pressure measuring technology.

If pressure was measured at all- way back then- the method was the copper crusher (CUP) which involved changes in length of a standardized piece of copper wire. The problem with crusher measurement is that it doesn't give true maximum peak pressure because of the simple mechanics. There is a certain lag time in the reaction of the copper so what you end up with is sort of an "average" pressure.

When the piezoelectric conformal transducer came into use there was a big "uh-oh" throughout the industry when everyone saw that actual pressures were much higher then previously thought.

Of course the reloaders who just hadn't had a gun blow up yet immediately presumed there was a vast left wing conspiracy against them- some folks still believe that- and that the industry was run by a bunch of sissies.

Actually the pressure limits established ages ago are largely unchanged but you will see a higher number for true "psi" and the original "cup" limit as well.

 

[csmkersh]

Thanks, Charlie.

While I wouldn't use my old load in my S&W M36, I'd use it in a .38-44 if I owned one. I'm not quit a brave as Elmer was. He finally figured out he could push a .44 Special SAA a little further than a .45 Colt because of the very slightly thicker cylinder walls.

 

[Charlie Petty]

I do own one and I wouldn't use it.

In fact that's a maximum .357 load and when you put it in a .38 Special case the pressure is probably considerably over the max.

 

[csmkersh]

OH... :banghead:

The old Lyman max load was 16.0 grains of 2400.. Think I'll mark the manual "Do Not Use Even In Emergency."

 

[Charlie Petty]

I concur...

Doesn't that sound suspiciously Elmerish?

 

[Charlie Petty]

Just for grins I ran a couple of loads through the computer...

A .357 with 16.0 gr. 2400 and a 158 gr. JHP gives ~50,000 psi

the same load in a .38 Special case has 59,700 psi

The SAAMI max for the .357 Magnum is 35,000 psi.

 

[csmkersh]

I guess I owe Thor and a Saint whose name I should remember a little or maybe a lot of thanks. I have no idea how many rounds I put through my Ruger flat top using 12½ grains as stated in my first post. :shock: