Some changes aren't an improvement

Once upon a time, the SAAMI (Sporting Arms and Ammunition Manufacturers' Institute) pressure standard for the old .30-30 was 38,000 cup (copper units of pressure). That’s according to Speer #10, page 214. That amounts to 7,000-8,000 cup less than the .357 Mag, by the old SAAMI pressure standards (some say as much as 46,000 cup being the max). Since the piezo transducer method of measuring pressure does have a 3% error and the copper crusher has a 5% error, it still doesn’t add up to the current specifications!

The current SAAMI standard is 42,000 psi for the .30-30, however, the current standard for the .357 Mag is 35,000 psi. What I’m trying to figure out is how the psi pressure goes up by 4000 for the .30-30 and goes down 11,000 for the .357 Mag, when both are compared to cup units of pressure?

Some seem to think there’s some sort of voodoo that is in effect with hand gun cartridges, that makes them behave different than rifle cartridges. Voodoo aside, pressure is still pressure, especially if it’s derived by using the same method.

If the copper crusher method had been thoroughly discredited, there wouldn’t still be a reference of 38,000 cup in Speer #13, page 263 for the .30-30. So, it can only be concluded that copper crusher pressures are still within the standards allowed by SAAMI. That also means the .357 Mag is a higher pressure cartridge than the .30-30 when measured by copper crusher, and there’s no getting around that fact. It’s also a fact that more pressure can’t be less pressure, regardless of the logic being used and/or the higher degree of accuracy afforded by using a piezo transducer.

The copper crusher method was the dominant standard until sometime later than 1975. If the general run of loads in pre-1975 publications is higher than what we see now, that should be ample indication of things being downloaded despite the protestations of SAAMI and their minions.

A look at the 1971 Sierra Reloading Manual, page 205, shows a 125 gr bullet in .357 Mag using 19.0 gr of Hercules 2400 and a CCI 500 primer for 1500 fps. For some reason this is showing up as a suspect image site, but the site is mine, so try this link instead http://www.bbhfarm.com/albums/album16/aab.sized.jpg

A similar bullet in Speer #13, page 528 says (the Alliant website duplicates this data) 17.5 gr produces 1409 fps using a CCI 500 primer.
Reloader's Guide Alliant Powder Reload Recipes

Pistols and Revolvers
357 Magnum * 125 gr Speer GDHP

Minimum OAL (inches) Bbl Length Primer Powder Charge Weight(grains)

Velocity
(fps)
1.58 10 CCI 500 Unique 9.6 1,343
1.58 10 CCI 500 Power Pistol 10.5 1,345
1.58 10 CCI 500 2400 17.5 1,409


Speer #8, from 1970, page 371 says 19.5 gr of 2400 with a CCI 550 produces 1514 fps using the same bullet as Speer #13. For some reason this is showing up as a suspect image site, but the site is mine, so try this link instead http://www.bbhfarm.com/albums/album10/aap.sized.jpg

That’s two copper crusher loads using 19.0-19.5 gr of 2400 with one piezo transducer load at 17.0 gr, so there’s a minimum reduction of 2.0 gr, or roughly 10%, using the same canister powder.

So, let’s look at another powder, Unique, using those same 125 gr bullets. Speer #13 says 9.6 gr with a CCI 500 at 1343 fps. Sierra says 10.0 gr at 1500 fps with a CCI 550 and Speer #8 says 10.5 gr with a CCI 500 at 1545 fps. Again, the later publication uses less powder than the earlier publications.

Further comparisons are difficult due to the powders being reported on having changed over the years, not in composition, but with common powders in the 1970s being out of production now, i.e. Alcan powders.

There are two conclusions for the reductions in powder weights, either the data from days gone by were dangerous due to incompetence on the part of the testers, or the standards have changed to a lower actual pressure.

My experience with Speer #8 loads indicate real world velocities that pretty well agree with what they got in 1970, not what they report now.