I just got my S&W 3rd gen back from the smith after a new barrel was installed b/c the original had a heavy land which caused the round to strike very low below my POI. Anyway, that problem was fixed with the new barrel however my rounds still strike about 1.5 inches low and 8-9 yards. I have heard that a heavier round such as 147 grain vs my usual 115 would raise up the POI. Is this true? Can I use 147 grain FMJ ammo to up my POI?