Scooter123,

From your post:

A few things to keep in mind.

First, the original 357 Magnum load featured a LEAD bullet. Note, lead has less friction in the bore than a copper jacket and that reduced friction is probably worth a 100 fps difference.

I have posted this information many times, the last was in my post in this thread.

Second, when it was originally developed the only means of measuring pressure was the old Copper Crusher method. A method that really only measures the AVERAGE pressure but does NOT measure near instantaneous spikes in pressure.

True, but millions of rounds have been fired with no problems, at the pressures determined by this method. It is just as valid as it ever was! And, it has nothing to with the current discussion of velocity.

Third, those 1500 fps velocities were probably the result out of a 10 or 12 inch barrel and longer barrels will increase the measured velocity. There is also the simple fact that the means for measuring velocity today are undoubtedly much more accurate that what was used in 1935.

These are both absolutely untrue. Original chronographed velocities were determined by shooting the cartridge in actual revolvers with 8 3/4" barrels, not from universal receivers or longer than standard barrels. You want to know more about development of the .357 Magnum? Then read Phillip Sharpe's "Complete Guide to Handloading" originally published in 1937. There is an entire chapter specifically about development of the .357 Magnum. Mr. Sharpe played a direct role in development of the cartridge, both with S&W and Winchester. His information is as "Straight from the horses mouth" as anything available anywhere!

Contrary to modern "lore" electric "Counter Chronographs" were available in the 1930s. They are far slower than modern chronographs (Ever wind wire screens? I have!). The tables would only give velocities in 10 FPS increments, but this hardly constitutes being less accurate. Shoot the same load over different chronographs available today and you can see far greater variation than this from one to another. Even the same machine on different days and conditions!

Finally, velocities in the 1500 FPS range are very doable in the .357 Magnum, from an 8 3/8" barrel. I have shot many rounds of 15.3 gr. 2400/158 LSWCGC from 2 different 8 3/8" Model 27s bought specifically for this purpose. Depending on conditions and which gun this load developed from 1498 FPS to 1530 FPS uncorrected. Corrected to the muzzle adds another 10 FPS approximately! If you don't believe it I can show you the chronograph date from my Oehler Model 35-P. The velocity variations I have posted here and before are not what I read in a magazine or on the internet, they are actual experience from shooting hundreds of rounds over the chronograph so I would have a personal grasp of the true effects of changing bullet type and lubricants on .357 Magnum.

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Gunsmithing since 1961