M4 motorway M4 motorway The M4, a motorway in the United Kingdom running from west London to southwest Wales, was originally referred to as the London-South Wales Motorway. The English section to the Severn Bridge was constructed between 1961 and 1971; the Welsh element was completed in 1993. The Second Severn Crossing officially renamed the Prince of Wales Bridge, was inaugurated on 5 June 1996 by HRH The Prince of Wales and the M4 was rerouted. Apart from its two spursthe A48(M) and the M48the M4 is the only motorway in Wales. From London to Bristol, the M4 runs close to the
M4 carbine Army that adding the Rail Adapter System (RAS) turns the weapon into the "M4 MWS" or "Modular Weapon System". The "M4A1" carbine is a fully automatic variant of the basic M4 carbine intended for special operations use. The M4A1 was introduced in May 1991, and was in service in 1994. The M4A1 has a "S-1-F" (safe/semi-automatic/fully automatic) trigger group, while the M4 has a "S-1-3" (safe/semi-automatic/3-round burst) trigger group. The M4A1 is used by almost all U.S special operation units including, but not limited to, Marine Force Recon, Army Rangers, Army Special Forces, Navy SEALs, United States Air Force Pararescue