“The Spanish Astra 400 was commonly chambered for the 9x23 cartridge. Some models were stamped 9mm/.38, and would reliably fire .38 auto cartridges as well...” [marktwain, post 39]
Astra’s 400 was chambered for 9mm Largo (aka 9mm Bergmann-Bayard), which is not the same as today’s 9x23mm (introduced 1996).
38 ACP is semi-rimmed but has been known to feed and cycle the 400. 38 ACP pistols (M1900, M1902, M1903 Pocket Hammer) went out of production at Colt’s in 1929, when the 38 Super Auto was introduced. 38 Super develops higher pressure than 38 ACP and should never be fired in the earlier guns.
38 ACP is tough to come by these days; it has the same external dimensions and bullet as 38 Super, and ammunition can be handloaded to the lower pressures/velocities safe in 38 ACP pistols.
Users are advised to exercise extreme caution. Avoid firing 38 Super in the 400.
Yes, the 9x23 or 9mm Largo, is loaded to different specifications than the 9x23 today.
You can use the 9x23 brass to reload 9mm Largo, which gives ballistics about the same as a 9x19.
Do not fire modern 9x23 in the Astra 400 pistols, or the Berman/Bayard pistols.