Here's what happens to a suppressor on an M249 SAW after firing 700 rounds nonstop Alex Lockie Mon, Jul 10, 2017, 4:58 PM m249 saw suppressor (This is a bad idea.West Coast Armory via Youtube) ...

The M249 fires a 5.56 mm round, and the Army is currently examining rounds of intermediate caliber between 5.56 mm and 7.62 mm to be used in both light machine guns and the eventual replacement ...

Like the XM5, the XM250 will be available by 2023 and officially become the M250. However, the M249 will remain in service until the M250 entirely replaces it.