For the store—purchased—variants of the Bizon and AKS-74U, their muzzle devices cannot be removed until the weapons are purchased. This forces players to purchase the muzzle devices alongside the weapons; players wanting to use different muzzle devices, or run suppressors only, are forced to purchase a muzzle device they do not want to use. This issue is encountered at every attempt on both new and old saves, including saves from 0.10.
To observe this, walk into the store, grab either a Bizon or AKS-74U, then attempt to remove the stock muzzle device; the muzzle device cannot be removed. Then, purchase the weapon; the muzzle device can be removed as intended.
I guess a sort-of workaround is shoving the weapon's muzzle towards the store exit until only the muzzle device is automatically deleted, but it's not too reliable.