The way I have been charging my .45-70 case were as follows. Throw the initial charge into a pan, place the pan on the Gempro 250 and trickle up to correct weight. The place my case on a electric engraving pen turn on the vibrator and slowly pour the powder int the funnel that’s on the case. I then measure the powder column height from mouth to a thin plastic “wad” that sit on the powder. If it not deep enough I vibrate again ‘till it is the correct height. Yes, very slow, but the column height is very close to nominal plus or minus .004 thou. The past few days I made up a vibrating drop tube gizmo. I now can easily get 83 grains of Swiss 1 1/5 in an unfired Starline .45x70 case, so I’m getting more compaction with the vibrator/Drop tube set up. The problem now is the height variation can easily exceed plus or minus .012 thou. The top funnel has a metering hole that is .061”, Smaller and the powder clogs on occasion, larger and the powder column variation increases further. I have a screen just inside the top funnel that I think helps cut down on poring variations. I hold the case in touch with the drop tube, it has an inverted cone the the case mouth rests against. Then I pour the powder into the top funnel and turn the vibrator on for a mental count of 8. With this procedure I get the plus or minus .012 inches. The way it stands now, if I set the COL to the nominal height my seating can go to .012 compression to .012 air space. Any hot ideas about cutting down on the variations in powder height ?
What are you fellows getting for powder column variation? Should I be worried about this as in decreased accuracy. I’m thinking I may not see any change in group size inside of 600 yards but then I don’t have the experience to make any sort of WAG.
As an aside I’m going to pick up a RCBS Chargemaster Lite tomorrow and my Gem Pro 250 still drifts so I constantly need to re zero.
Thanks Folks