I wouldn’t particularly mind the change, but Grudge already has the big advantage over BB of getting to shoot twice before having to reload. RV also has access to better reload speed via his passive and Firing Fury, making that build very strong as is.
Then you also need to consider how this would interact with Survivalist caches. With 20 base ammo RV would get 3 shots from standard caches and 9! with Grugni’s. It would open him up to taking pot/bomb talent or even ales without giving up too much sustained fire, especially combined with the new Scrounger break point you raised.
All in all this might be too much of a buff to the already very strong grudge RV build. This is just my theory crafting though and I’m not all that experienced with RV, so take this with a grain of salt, but whenever I have played Grudge RV it’s felt plenty strong to me.