BMG rifle is only .50 inch (12.7 mm) across the rifling lands and slightly larger in the grooves. The oversized bullet is formed to the bore size upon firing, forming a tight seal and engaging the rifling. Subject to political controversy due to the great power of the cartridge (it is the most powerful commonly available cartridge not considered a destructive device under the National Firearms Act), it remains popular among long-range shooters for its accuracy and external ballistics. While the .50 BMG round is able to deliver accurate shot placement (if match grade ammunition is used) at ranges over , smaller caliber rifles produce better scores and tighter groups in competitions. A 1999 Justice Department Office of Special Investigations briefing on .50 caliber rifle crime identified several instances of the .50 BMG being involved in criminal activities. In the United States, Washington, D.C. disallows registration of .50 BMG rifles, thus rendering civilian possession unlawful. California prohibits the private purchase of a rifle capable of firing the .50 BMG through the .50 Caliber BMG Regulation Act of 2004. Connecticut specifically bans the Barrett 82A1 .50 BMG rifle. However, .50 BMG rifles registered prior to the enacted bans remain lawful to possess in California and Connecticut. In Illinois, it is legal to possess a .50 caliber rifle only if it was acquired by January 10, 2023, and it is registered with the state police by January 1, 2024. Maryland imposes additional regulations on the sale and transfer of .50 BMG rifles and other "regulated firearms", and limits purchases of any firearm within this class to one per month, but does not impose registration requirements or any form of categorical ban. Contrary to a persistent misconception within the United States Armed Forces, using .50 BMG directly against enemy personnel is not prohibited by the laws of war. Writing for the Marine Corps Gazette, Maj Hays Parks states that "No treaty language exists (either generally or specifically) to support a limitation on [the use of .50 BMG] against personnel, and its widespread, longstanding use in this role suggests that such antipersonnel employment is the customary practice of nations." Parks theorizes that the misconception originated in historical doctrine discouraging the use of the M8C spotting rifle—an integral .50-caliber aiming aid for the M40 recoilless rifle—in the antipersonnel role. This limitation was entirely tactical in nature and was intended to hide the vulnerable M40 and