To me own self, there is really precious little that gun-writers can write that is "new" or different. So through time they must re-hash or invent.

Some of them escaped a certain amount of those "requirements" because they wrote stories connected to use of firearms and not about firearms minutiae itself.

Such as Skeeter Skelton and Jack O'Connor. They wrote more about what the guns would do than what was the latest, most efficient cow-killer.

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Have guns...will shoot'em.