Somewhat different topic, but relevant information here
https://www.doublegunshop.com/forums/ubbthreads.php?ubb=showflat&Number=621506 SAAMI max. for 20g 2 3/4" and 3" is 12,000 psi
You are correct re: CIP 20g service pressure. The Max. Statistical Individual Pressure however is 950 BAR or 13,779 psi
THIS IS IMPORTANT: We have
no data on the pressure rise when using longer than chamber 20g or 16g shells, which run higher pressures than 12g.
Bell's study can not be cited as evidence of the safety thereof.
So none of us have empirical evidence, but I'll give you my opinion, and other opinions are certainly valid:
I'd stick to 7/8 oz at 1200 fps in loads with cases measured at 67 mm
If there is no feathering of the case mouth, I wouldn't worry.
