[mehavey]

Originally Posted by BART B

MIL-SPECS for the 5.56 NATO M193 round:
http://www.everyspec.com/MIL-SPECS/M...C-9963F_25766/

PUBLICATIONS
SCATP-5.56 - Ammunition Ballistic Acceptance Test Methods,
Test Procedures for 5.56mm Cartridges....

3.7 Chamber pressure.

3.7.1 Measurement by copper-crush cylinder.
-The average chamber pressure of the sample cartridges, conditioned
at 70° ± 2°F, shall not exceed 52,000 pounds per square inch (PSI).
The average chamber pressure plus three standard deviations of chamber
pressure shall not exceed 58,000 PSI.

3.7.2 Measurement by piezoelectric transducer.
-The average chamber pressure of the sample cartridges, conditioned
at 70° ± 2°F, shall not exceed 55,000 PSI. The average chamber
pressure plus three standard deviations of chamber pressure shall
not exceed 61,000 PSI.

Well.... finally we have apples and apples..... and it turns out SAAMI's 55,000 (true) psi is good2go