M4 corridor bridge, serving Chepstow, being renumbered the M48, although the area is still generally considered as falling within the M4 corridor. Since the start of the 21st Century there has been evidence of more investment west of Cardiff, such as: M4 corridor The M4 corridor is an area in the United Kingdom adjacent to the M4 motorway, which runs from London to South Wales. It is a major high-technology hub. Important cities and towns linked by the M4 include (from east to west) London, Slough, Bracknell, Maidenhead, Reading, Newbury, Swindon, Bath, Bristol, Newport, Cardiff, and Swansea. The area is also served
M4 carbine weapons through 2011. However, a number of other manufacturers offer M4-like firearms. Colt previously held a U.S. trademark on the term "M4". Many manufacturers have production firearms that are essentially identical to a military M4, but with a 16" barrel. The Bushmaster M4 Type Carbine is a popular example. Civilian models are sometimes colloquially referred to as "M4gery" ( , a portmanteau of "M4" and "forgery"). Colt had maintained that it retains sole rights to the M4 name and design. Other manufacturers had long maintained that Colt had been overstating its rights, and that "M4" had now become a generic