So I figured out what that little washer "adapter die" does

on a Lyman 310 tool. It ensures concentricity of the case with the die. This does things such as prevent breaking de-capping pins etc. (ask me how I figured that out) The handles can push on the bottom of long cases at an angle. If the case is not supported it indeed is at an angle starting into the die body and may be misaligned. With care it can be deliberately overcome but the adapter die part does serve a purpose.

Using slower pistol powder for cast applications I broke out the 1/4' thick Dacron blanket stuffing. As directed by the manual. One benefit is after application (stuffing it against the powder with a pen) is that it cannot spill.

I have had this package of stuffing for over a decade (not even close to making a dent as yet) and also used it in .303, .30/40, .30-06, .470/500 Nitro etc. as well as varied Reeder GNR's for light loads or fireforming. Tissue or paper will catch fire! Dacron is good stuff that works while adding no notable weight to the projectile or charge and does not melt nor combust, it just blows out. Even with a chamber break it just blows out the holes. These squares will likely be cut in half again.

I have always enjoyed the #310 priming system. Its fun.