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Yes, more useful at a glance to have graphs "velocity vs inch"

Yes, about 8"-10" going by the "Ballistics by the inch" page, with some differences between different kinds of ammo. Most bullets still pick up slightly even out to 17" 18" barrels. So not bad for...

Of course we don't know how much 9mm he is sitting on, never mind reloading gear etc etc (-:

The de Lisle could have been made in .303, scoped, issued with only a small amount of rare-use...

Here is a Russian revolver shotgun, double action, available in 12, 20, 28, 32 gauge and .410 bore. Wikipedia article.

118039

Or revolver rifle, break barrel for easy stowage as well as that Webley wonder of six simultaneous extraction pings.

https://www.nzhuntingandshooting.co.nz/f53/9mm-rimfire-bolt-action-44538/