Joe
  Go to the local hardware or marine supply store and buy a piece of non-skid material. It will have adhesive backing. Stick a piece of it on the flat clamp area of the Belding and Mull measure and the slipping problem disappears. Mine is as solid as a rock.

Bill

Another question on the B&M.......... How many times do you pass the powder chamber over the powder measure? 

Three times for me. I like to see that it's completely refilled and it compacts the powder in the measure a little.

Frank

Frtank
I only use the B&M with course powder and weigh each charge. Dont make any differenc how many times I move the handle as long as the tube is tight against the measure first time. I use the knocker on both strokes of the handle.

Tom

Black or IMR stick powders I pass it one time and check weigh every 10th charge.

55's  do have a knocker. It's all technique and some guys can get good results with 55's.  All 55's are not the same though. My first one was not a good one probably 1980 production.  Junk box at the Club swap meet I picked up a real old one with a broken handle.  Stripped it for parts and did some switching with the  new measure. It works a lot better now, drum  from the old measure is more precise. I do OK with the 55 and perhaps it's the best compromise measure black and smokless.   

Dedicated I go with a Harrells for 4227 & Varget The B&M for Black & 4759.  Old Bonanza fixed rotor for Unique and Hodgen Clays pistol powders. Down to 6 powders now.

Boats

Screwloose By precise I mean the fit of rotor to body. My newer Lyman the steel rotor fit's in the cast body. Old one has a cast body that's bushed with brass, much nicer fit than the newer 55.  Thing thats catching me with my 55 now is the screw on the offside of the drum is  backing out and giving trouble. I could loc Tite it but need to take it apart to clean when using black powder

3 different venier settings on a 55 are so difficult I never use it for anything. Like you always set with a balance beam scale that's been calibrated with check weights.

I follow that policy with everything even fixed rotor bonanzas. I might make a mental mistake setting up and the beam balance scale will catch the error.   

Good 55 is a good measure though.

Boats