[DonVoigt]

John,
I addressed your questions in the initial post.
The pressure of the .45acp is about 65% of that of the 9mm p, and so is the energy.
Having converted and fired the 9mmP version, I feel quite "comfortable" with the much lower pressure and energy of the .45. The SAAMI pressure for the 9mm P is 35K psi and for the 45 only 24K psi.

I consider the 9mm P version sufficient "proofing" of the concept given the much lower pressure and energy of the .45.

Historically both the Indonesians and Koreans(North IIRC) converted and used the Nambu in 9mm P for a short time after WWII.

I can find no pressure measurements for the original 8mm Nambu round. But it's energy can be determined from wt x velocity.

Just a pedantic note, cartridges do not "detonate", smokless powder burns at a rapid rate; maximum pressure is reached if/when all the powder burns before the bullet exits the barrel. What is measured and specified is "peak" pressure, measured at or near the chamber, at least that is my understanding from what I have read.