The NRA publication "Handloading" says that dacron fillers ring barrels and not to use it.

I have used kapox with success in various 375's and powders like IMR 3031.

If you load your reduced 416 Rem Mag loads with XMP 5744 you won't need any fillers. It is not position sensitive. It is a God send to all of us who load light cast loads in the big bores.



If you use another powder that requires a filler you can get dacron from any fabric store. It is used as batting and stuufing for pillows, dolls, stuffed animals, etc. Make sure it says Dacron on the label.

JCN



Edit to above. BruceB knows way more on this subject than I do. Please see his new thread.

JCN