Recent news coverage has made it explicitly clear that the U.S. Marine Corps is finally going to upgrade legacy 40x46mm low-velocity M203 under-barrel grenade launchers to the much more mobile and versatile Heckler & Koch M320s that the U.S. Army has successfully been using for a number of years to date. Current numbers indicate that 7,000 are wanted by at least 2019, and at the latest in the year of 2022 for a force-wide issue among both the Active Component in the Fleet Marine Force and in the Reserves as well. Currently an article on Marines.mil is showcasing elements from 2nd Combat Engineering Battalion at Camp Lejeune working with M320s as a test case.
The M203 as it currently stands never really had any major issues that lead directly to an urgent need to upgrade the system and this is probably why there really isn’t a rush in getting the M320 into the Fleet. That, and little brother budget issues of course. Most of the M203s I encountered while in the service worked very reliably, and were very simple to maintain and clean. Although the ammunition length issue is absolutely true, we never had 40x46mm grenades that went over that length. But I can see baton rounds becoming useful for civil disturbances within some units overseas, and the M320 opening that opportunity up. In addition, having a mobile grenade launcher will most likely be the largest asset that this change brings into play. This means that instead of switching out 203s within a squad, or even just requiring a rifle to be armed with a 203, the M320 can now be a mobile unit, leaving it on post for example.