The term pinned and welded typically refers to the attachment method of a rifle muzzle device. In most cases, muzzle devices are removable via a threaded attachment system, but in some cases, manufacturers pin and weld their muzzle devices to the end of the barrel so they cannot be removed. This is typically done to conform with federal law defining the minimum length of a rifle that can be purchased without additional federal licensing or tax stamps. With a muzzle device that is pinned and welded and therefore cannot be removed, the length of the muzzle device counts towards the overall length of the firearm for legal classification purposes.