yes that will make it 3 tenths end fall.    but keep in mind that just because it says 0.30 on the gauge it doesn't mean that it is exactly 3 tents fall.  some gauges are not exact. like I mentioned before on top of the transmitter uslly the handle you grab there should be a arrow upslope pointing one way and another pointing down slope.  if it doesn't do what was mentioned and set your gauge at 0.00 messure out 3 hundred feet and make a mark on where the light is hitting and then dial in 0.30 and it should move down about 3 inches.....    then you know.   I have a set of permament mirrors set up in my shop that I bounce the light off of. with mirrors I can calabrate my transmitter and don't have to walk to check where the light is hitting.  with enough mirrors you can make a 100 foot shop into a 1000 feet line of sight...…….  all you really need to make sure is there is no side fall in your transmitter.     Clear as mud?