John is my friend, and I find we agree on many, even most, things. He used to like heavier loads than me.
Bear in mind too, that when using 2400 in your .357 or another cartridge, regular primers will lower pressure from Magnum primers. The old timers never used Magnum primers (they didn't exist then), thus their loads reflect this. In his last days Keith commented regarding his famous load of 22 gr.( of old) 2400 with a 240 in the .44 Magnum, that if magnum primers are used with 2400 that the charge should be dropped 1 grain, and if jacketed bullets were used, it should be dropped 1 more grain.
I just got back from the range with some surprising results....
I loaded some 180 gr Missouri Pugnose coated bullets in starline 38 spec brass. The primers are cci 500 small pistol. I never use magnum primers in my 357 or 44 mag.
I dropped the charge to start at 9.0 grains to be on the safe side as you advised,
Thanks again for the info. Id rather crawl up to heavier charges than jump in blind folded.
Here's my results with 2400
9.0 gr 875 fps
9.5 gr 930 fps
With the above 2 loads they were very soft loads with no primer flattening at all. What I was worried about was the smaller case capacity of the 38 case and that I would see a spike. I went back home and loaded 10.0 grs as well as took the original 10.5 gr
10.0 grs 970 fps
10.5 grs 1005 fps
As with the first 2 loads they were very nice to shoot. Not so much on accuracy (about 3" at 25 yards). The same result happened with the primers. Minor flattening with still a good bubble curve on the primer.
Im not sure what to think about edging up in .2 grain increments. I do not feel safe with the original 13.5 gr load nor do I even want the velocities that Taffin recorded. But given the math it seems right on course with his velocities.
I just feel that much like a 22 hornet the pressure spikes can happen with just a small increase.
Im going to try 10.7 10.9 11.1 next and see where I am at.