The M240B is being tested with a new adjustable buttstock that may replace the current stock of the M240B. The lighter M240L has started to replace the M240B in US Army service. The Marine Corps is observing the progress of the M240L, but feels it is too expensive for adoption. The corps is instead looking to upgrade the M240 barrel through several ways, including carbon fiber coatings, new alloys, or ceramic liners, to lighten and strengthen the barrel. The goal would be a barrel that would not need to be changed, would weigh the same, but decrease heat retention, lessen warping, and eliminate cook-offs. They are also interested in incorporating a suppressor into the barrel, rather than having to attach one, to reduce the sound of shots and make it difficult to determine where the gunner is located.