Note that in the quote that I posted above, from Linebaugh, he stated that he prefers to keep his 45 Colt loads under 25k psi in N-frames.
I have an article written by Brian Pearce about the 45 AR. This was in the August 2008 Handloader magazine. In that article, he stated that there are really no "weak" revolvers in 45 ACP, with each designed to handle the SAAMI spec of 21k psi. And +P being 23k psi, and safe in revolvers of proper working order. I suspect that the same is true of N-frames chambered in the Colt cartridge.
So, it would seem that 23-25k psi is reasonable for an N-frame based on Linebaugh and Pearce. If you want more details on that Pearce article, let me know.
