Loading small quantities of powder in a large case has always been one of my favorites for plinking and loads for the kids to shoot out of high power rifles and handguns.
When I first started loading these low density loads in high volume cases there were occasions when primers would be gone when the cases were ejected, not a good feeling. I did a lot of researching, communicating with many gun writers and found there was a thing these folks referred to as "flash over" where the primer flame ignited the powder at the base of the bullet and burned back to the primer hole, creating a pressure spike. Strong actions seem to keep everything contained, so there really doesn't seem to be much problem, but accuracy really suffers.
I did a lot more research and found that a wad over the powder to keep it closer to the flash hole would improve accuracy and seemed to allow a healthier dose of powder and also kept the primers where they belong.
Now this is just what I have observed.
I have loaded a 130 cast bullet in a 300 Mag case with 15 grains of Unique and gotten accuracy of 1/2 minute at 100 yards with the recoil of a 22 long rifle.
I did a lot of experimenting with wad material, most were a real mess to work with, what I have finally settled on look like ear plugs, (I wouldn't use them for that tho) these are cut from insulation foam with a case that has been cut of and sharpened (drill the primer hole so there is room to get something in to push the wad out). Roll them between your fingers and insert them into the case mouth, allow them to expand, then seat them over the powder charge with something will fit into the case mouth.
Ray
