Latest I've heard from Knox: the Stryker's General Dynamics promoters have a cure for the vehicle's unsuitability for use with the Mk 19 grenade launcher: do away with the Mark 19, and switch over to a *new and improved model* Mark 47 40mm auto grenade launcher instead.
Coincidentally, of course, the builder for the Mark 47 is General Dynamics.
It may be that the Stryker's incompatability with the Mark 19 was designed in from the get-go.
-archy-/-