agree w/ firearmdoc about consistency, have a pair of 55 one dedicated to bp the other smokeless, haven't used anything else except the measure that came w dillion loader, works well for me,  as far as using the knocker, I took it right off, don't run any real slow powders (4831/4350) good luck

The problem with 4759 is the size and shape if the grains. It is extruded in the shape of a relatively long stick. This leads to a couple of problems when trying to meter small amounts of powder. When the powder drops into a small chamber it doesn’t have room to settle and will give different weight charges as the grains randomly distribute in the chamber. Using the knocker will help some but only if the measure is open when the knocker is used. The larger the chamber is adjusted the more room the powder has to move around and settle. That is why the B&M measure has a good reputation The size of the metering chamber remains the same roughly 3/8” hole and gets deeper as the charge gets larger. For me the break point is about at 38-55 size charges below that it is almost useless to drop charges in a measure with an oblong chamber such as a Lyman 55. 
The other problem is powder bridging when the jumble of tiny sticks turns into an obstruction in the drop tube. This usually gives a short charge on one shot and an oversize (sometimes dangerous) charge on the next.
  The best way to get an accurate charge weight is to drop the charge and then trickle it to the proper weight. This is time consuming and tedious and does not lend itself loading at the bench. All in all there are now powders that meter better in small amounts than 4759 for the traditionalist it will remain a go to powder for the time being.

40 Rod

I added a baffle to mine and it definitely helped with consistency by keeping the weight of the powder column consistent on  the powder chamber.  Another comment - when finished using black powder, its a good idea to remove the metering drum and clean the powder residue from the drum and iron casting. If you live in a humid environment, if the residue is not removed, it may cause rust.  I know by experience

Ive loaded everything from bullseye to some pretty rough stick powder.  Just be consistent and try to eliminate as many "steps" in the drum as you can. I like for the top two slides to be aligned if possible.

I don't have a baffle but what I do is raise the handle, rap the reservoir twice with the knuckle, drop charge, and flip the knocker twice.  All this is done much faster than I typed the first four words.