And those that operate on straight blowback, such as the ones in .22 and 9mm, dispense with the buffer tube all together. Not sure about the ones in the FN 5.7 caliber- which IS a pistol cartridge that WAS designed to defeat soft body armour.
Yes, there are. And barrels are available as short as 7.5" for them. They don't have stocks, but use a buffer tube coming out the back in order to fit the definition of a pistol.
And those that operate on straight blowback, such as the ones in .22 and 9mm, dispense with the buffer tube all together. Not sure about the ones in the FN 5.7 caliber- which IS a pistol cartridge that WAS designed to defeat soft body armour.