There is no SAAMI spec for max pressure in 9x23, but...
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I wanted to see how much power I could get.
For a while I was shooting:
1) 158 gr LSWC, 1.36", converted Tokarev, Starline 9mm Supercomp brass, and 20 gr of LONGSHOT.
Given that the max powder charge for that bullet in 357 mag is 8.5 gr, one would think that would give more power than:
2) 158 gr XTP, primed Win 9x23mmWin brass, 16 gr Power Pistol.
But even though the max load with that bullet for 357 mag is 8gr, the Power Pistol load is more powerful.
I have also converted a Star Super B, but all it has shot is 10 gr LONGSHOT, 158 gr LSWC, 1.3".
Here is a synopsis of experiments in pursuit of max power:
9x23 with chamber support that reaches the web, and extra throat:
I worked up loads until the brass failed or I could fit no more powder with:
Win brass, 130 gr. 3N37 ...primer falls out
Win brass, 130 gr. N105 ...case full
Starline brass, 130 gr. Power Pistol ...case full and primer falls out
Starline brass 130 gr. N105 ...case full
Win brass, 130 gr. LONGSHOT ...case full
Win brass, 147 gr. 800X ...case full
Starline brass, 147 gr. 800X ...case full
Starline 147 gr. Blue Dot ...case full
Win brass 147 gr. Power Pistol ...case full
Win brass 147 gr. LONGSHOT ...case full
Starline brass 158 gr. STEEL ...case full
Starline brass 158 gr. LONGSHOT ...case full [Double compression]
Starline brass 158 gr. Power Pistol case fails
Win brass 158 gr. Power Pistol ...case full, double compression
I have not chrono'd the loads, just compared by recoil.
I HAVE chrono'd a .380 load that is similar: 8.5 gr Power Pistol [all that will fit] 158 gr XTP, 1.090", 1187 fps
From what I know about handloading, I realize that even more power is possible with double compressing 800X. I have not done that with 9x23, but I have with .380, 40S&W, and 10mm.