Hi all, a very interesting topic.
I'm primarily a powder burner but events have led me into the airgun world with a vengeance.
Having chased my tail with several high quality airguns over recent years I'm onto an Impact in .22
AFAIK most powder scales are accurate to 1 tenth of a grain, so is it worth using them? I've tried using $1800 lab scales that will have you running to ever finer divisions with no discernable return for the effort.
IMHO and limited experience I’ve found that head size and skirt roundness/ratio seems to return the most gains with regard to effort v gain. My rifle running at 901fps with JSB 18.13gn will shoot very well; certainly good enough for my vermin control needs.
My barrel likes a small head size, 5.49mm to be exact. That means I have to put each pellet through a re-sizer which takes about 1 second per pellet.
The two 50yd groups below were enough to persuade me to just wash, lube and then re-size. After spending some time trying different head sizes I shot the two groups below. Although they are nothing special size wise, I think they do show gain v effort nicely. The one on the left is un-sized, the right hand group was shot using sized pellets from the same tin.