Sounds like you had some of the same problems with the grenade launcher many people have complained about. If you want a suggested house rule for toning them down a bit I posted one on my blog here:
https://sanctumreconditesage.blogspot.com/2021/08/stargrave-grenade-house-rules.htmlThey seem to work okay, but I haven't gotten the dubious pleasure of testing them against some maniac who's spamming seven grenade launchers yet. For more restrained games where you might see one or two launchers and some hand-thrown grenades they make bunching up for combined activations a bit less suicidal.