Ok, I feel like I'm aiming at a moving target.
Let's get back to how this started.
Originally Posted by SL1
But, I still blame SAAMI for creating the situation where a cartridge that was designed to produce 1500 fps with a 158 grain bullet from a 8-3/8" barrel is now not able to produce more than 1250 fps from a 6" barrel.
This quote is in error 2 ways.
First of all, it's not really accurate to say that the "cartridge was designed to produce 1500fps with a 158grain bullet" because it never really did that except with long unvented test barrels. I pointed that out and you brought up the WW-296 load as an example of why it really was designed to make 1500fps with a 158grain bullet. HOWEVER, it turns out that the velocity figure you listed as evidence was STILL from a test barrel and, when shot through a typical 6" barrelled revolver it shot nearly 300fps slower (doesn't make 1500fps) per the test data on handloads.com.
Second it's not really accurate to say that it won't produce more than 1250fps from a 6" barrel because the load you listed actually produced over 1300fps from a 6" barreled revolver, again as listed on handloads.com.
So when I objected to your comment, you provided, in return, a lengthy (correct) explanation of why it's reasonable to expect that velocities in long unvented barrels will be a lot higher than what is seen in reasonable length barrels with actual cylinder gaps. I understand everything in your explanation and while it's correct, it doesn't change the fact remains that the numbers you tried to use as "evidence" to support your original statement that I objected to (i.e. The .357Mag was designed to produce 1500fps/158gr in a typical revolver but SAAMI changed things so that it won't do that any longer), don't support that claim.
While you may feel it's reasonable to blame SAAMI, it's quite clear that SAAMI doesn't have anything to do with why a load that shoots over 1600fps in a long unvented test barrel shoots about 300fps slower in a 6" barreled revolver.