Yes, the barrels are exchangeable between the Dark Mountain Arms single-shot rifle and pistol versions. The Stowaway platform features a removable barrel that allows for switching between different length barrels (rifle and pistol) or converting to other calibers by changing both the barrel and bolt face.
Detachable barrels: The rifle and pistol models have detachable barrels for portability and versatility.
Interchangeability: You can swap the rifle barrel for the pistol barrel by following the takedown procedure, which involves unscrewing the barrel nut.
Caliber conversion: The design also allows for caliber changes, which requires both a new bolt face and the new barrel.

Hi Ed, yes sir, the barrels are interchangeable.
Barrel Interchangeability of Dark Mountain Arms Firearms
Overview
Dark Mountain Arms offers a unique single-shot bolt-action firearm that includes both a rifle and a pistol variant. One of the standout features of these firearms is their modular design, particularly regarding barrel interchangeability.
Barrel Compatibility
Interchangeable Barrels: The barrels for both the rifle and the pistol are designed to be interchangeable. This means you can switch barrels between the two platforms, allowing for versatility in caliber and length.
Caliber Options: The basic model comes with a barrel in 5.7mm, with additional barrels planned for .22 LR, .22 WMR, and potentially other calibers like 9mm, .40 cal, and .45 ACP. Changing the caliber typically requires only a barrel and bolt replacement.
.
Stay safe & have a great day!

Hi Edward and welcome. Yes, the rifle and pistol barrels from the Dark Mountain Arms Stowaway series are exchangeable because the firearms are designed as a takedown system with detachable barrels. The process involves unscrewing the barrel nut, removing the barrel, and then installing the desired barrel from either the rifle or pistol version to change the firearm's configuration. Cheers, stay safe and enjoy!