The modern low-wall's are a different design from the originals. The modern low-wall has the receiver shoulders, behind the breech block, at or above the center line of the bore. This design change has more effect than the metallurgy.

The original low-wall has the shoulders significantly below the center line of the bore. This works like a post in a post hole. Fairly easy to crush the dirt at the top of the hole with a side load on the post.

The chart shown is a cropped version of the original. Cropped information included a caution about other effects than cartridge thrust, my name and date. The chart is based on SAAMI data to attempt to quantify the capabilities of an original low-wall. .357 Mag. was the largest cartridge found in print and knew of a cracked low-wall in .32-40.

My greatest concern with the chart was the mixing of more modern transducer pressure measurements with older Copper Units of Pressure (CUP), but did not see a choice.
Chuck

The modern low-wall's are a different design from the originals. The modern low-wall has the receiver shoulders, behind the breech block, at or above the center line of the bore. This design change has more effect than the metallurgy.

The original low-wall has the shoulders significantly below the center line of the bore. This works like a post in a post hole. Fairly easy to crush the dirt at the top of the hole with a side load on the post.

The chart shown is a cropped version of the original. Cropped information included a caution about other effects than cartridge thrust, my name and date. The chart is based on SAAMI data to attempt to quantify the capabilities of an original low-wall. .357 Mag. was the largest cartridge found in print and knew of a cracked low-wall in .32-40.

My greatest concern with the chart was the mixing of more modern transducer pressure measurements with older Copper Units of Pressure (CUP), but did not see a choice.
Chuck

Curves are based on bolt thrust, pressure times the area of the cartridge base diameter. Individual points for cartridges are from SAAMI base diameters and pressures.
Once the bolt thrust was established for a given cartridge, the base diameter was changed, area calculated, and the pressure calculated to establish the curve.
One could plot a similar curve for any cartridge on the chart.
Chuck

You are correct. Believe KSI is an acceptable and widely used abbreviation for 1000 PSI.
Chuck