Pls read - Standard vs Magnum Primers

[The Preacher]

Just as a side note:

I started loading 357 Mags about 35+ years ago. I eventually settled on 13.5 grs. of Alliant 2400 with a 158 - 170 gr. LSWC as my standard (mid-range) all around load. From the beginning I used CCI 550 mag primers as at the time that's what was recommended. My loads shoot great in every 357 mag I've had. Extremely accurate. Using a chronograph velocities are solid and as expected. ES is acceptable. In other words, no issues. Fast forward a few decades and I was told (read) that with 2400 in 357's use std. primers only. Much better for a number of reasons, all valid I'm sure. I thought about it a bit and decided why fix it if it ain't broken. Also, I use the 550 mag primers in my 38 Special +P loads with 2400 and 158 gr. LSWCs; Again with great results. I know this isn't anywhere near the "test" of the OP, but after all these years and in today's world of reloading I'm not doing the right thing.. but I'm more than pleased with what I've been shooting all these decades. Just food for thought.

Preacher

 

[mikejh]

An interesting article but a word of caution on the pressure measurements. I don't believe his pressure measurements should be used to compare against SAAMI specs. The method the author used to measure the pressure is nothing at all like what SAAMI uses, and is likely the cause of the huge variations he reported for specific loads. You cannot expect that a strain gauge mounted externally on a barrel can record comparable results to a CONFORMING piezo electric sensor, mounted in a drilled port into a heavy barrel in a test receiver such that the face of the sensor conforms to the chamber contour and places the sensor in direct contact with the expanded brass cartridge case. That's how SAAMI does it, and most hobbyist handloaders can't afford such equipment. I believe the author's tests acurately report the velocity variations but I wouldn't bet on any of the pressure measurements.

 

[DWalt]

This is a totally invalid and worthless test, best to ignore and move on. If you want to get really confused, just google about using strain gauges for chamber pressure measurements.