Yes, definitely. I'm sure you will find the MG will run slower than the plated Berry's. The charge you are using now might work well with a real jacketed bullet. You can lower the charge some if you like for the Berry's, just not too much.
Unique is a good powder for mid to upper range loads. You will find as your charge get's lighter, the powder will leave more residue and unburnt flakes. You can run some pretty light loads with a 14lb. spring, but I wouldn't go too light with the Unique or weapon and bullet performance will likely suffer. Most bullets need a bit of zip to stabilize and achieve the best accuracy.
Get a faster powder if you want to load just a tad over power factor. I think you will find eventually though, you can and probably will be happier when you stop chasing the elusive bunny fart.
Thanks, I will wait on the MG's and chrono again with the same charge.