I am back and see that all the advice I would have given has already been covered, and then some and better than I could have. Yea TFL team!
Does anyone know if the Berry's plated bullets are shorter than the Lead Round Nose the O.P.'s source (see post #3)?
If they are shorter, I would say that seating deeper by the amount of the difference would be safe. It is the free space beneath the bullet that is most important to pressure. The overall length you have feeds well in your gun, so I would be inclined to keep them there until you are ready to experiment.
The Berry's bullets are plated, and as I understand it, plated pretty heavily. So, it might be considered OK to treat it a little more like a jacketed bullet. But and it is a BIG BUT, as Mike Irwin pointed out, advanced or experimental ad hoc adjustments (like the heavier Win231 he advised against) are to be avoided while you are still getting your "sea legs". You don't have a ballistics lab or even a chronograph yet. It takes some experience and judgement (which mostly comes from experience) to discern the signs of overpressure or odd behaviors in loads that push the performance envelope.
I am being more candid with you than I usually am with new reloaders. So, take my cautions seriously and keep for a future date my comments that might encourage you to stray from published and vetted data. I discerned from your original post that you are a serious handloader, not inclined to take chances, so conclude that you can handle yourself, your guns and your loading with sense. I respect that.