Raketgevär-901-Improved Ammunition(2):khang36, WorldOfHurt
Teucer Rocket Barge (1): UristMcRiley
Bombsticks (1): MoP
I'm voting for the """grenades""" and you should too, because it'd be the cool and attractive thing to do. Also, it'd help across more areas than the rocket barge. Also also, the name of the revision isn't misleading like the Improved Ammunition revision that does more than just revise ammunition. A bipod
and a baseplate/exhaust deflector? Those are the most complex components in existence! Also also also, it's not a completely boring sane idea. I'm split between the explodables and sniper rifle though. As everyone who's played video games knows, snipers are the best at taking out machine guns (and more precisely than indirect fire), and that could help get more meat to the enemy trench. That said, the explodables will help more when the meat actually
gets to the enemy trench.
On a serious note of rocketrifle criticism, I'm not sure a baseplate/exhaust deflector combo is gonna be worth doing. It's gonna get in the way of reloading and is a lot of added weight while probably not changing the need to get up over the trench to fire, since the backblast is still going to be contending with the trench unless every bit of energy get directed straight up and out - and then that force is now being entirely exerted on the user as it slams against the deflector, . You might be able to sell it as an additional accessory that allows mortar conversion, but to deal with the issue of backblast we're probably going to need to use a counterweight or make a model that slingshots it out before the engine lights up. I think you'd be better off just focusing on the ammunition.