If google is correct, Rocky mountain mix is only 8% protein. You need a minimum of 12% to do any good at all. 16% is better. Protein pellets won't go thru a sling feeder due to moisture from rain/humidity. There is a corn soybean mix that brings protein up to 16%, so that is what I use in sling feeders. I use the "eliminator plate" as a spinner and a cage around the spinner to keep birds/squirrels/coons from getting to the feed. The plate and the cage virtually eliminates loss of feed between feedings.
In the summer months (period of growth of antlers) and when rain is lacking, I use a 1200 lb protein feeder with 3 ports. However, to be able to afford it, I close all but one port. Even with that, they eat 35 to 50 lbs/day in my area. Cost on that pushes $10/day for one feeder. Got 2 feeders so $15-20/day. I can stand that for about 3 months (june/july/august). At least I did this year. Will see how it goes.
In our area, the deer are going to stop coming to feeders this fall during the hunting season. We have a bumper acorn crop this year and when that happens, the deer disappear during the day. Kind of like that because my hunters are really going to have to HUNT this year.
venor, ergo sum (I hunt, therefore I am)