Specifically the [VBR-PDW](https://guns.fandom.com/wiki/VBR_PDW), the wiki article mentions that it can be rechambered to fire a different caliber cartridge, but wouldn’t that require replacing all of the guns internals (and externals) with 9mm compatible ones?
In: Engineering
The VBR is (or was advertised to be) available in two different calibers. Is in, you can buy the 7.92mm *or* the 9mm version from the factory.
It is common to offer the same gun in multiple calibers. This is not the same as designing around a hotswap caliber conversion feature.
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