The weather was warm and the sun was shining today, so I set up my equipment to test the IMR 4166 handloads I didn't manage to get around to Tuesday. Since I'm running out of actual targets, I decided to make my own using some 9" diameter paper plates, which I set up at 100 yards.



My load consisted of Hornady brass, Federal 210 Large Rifle primers, 58 grain Hornady V-Max bullets, and various charges of IMR 4166.

42.5 grains IMR 4166:

Average velocity: unknown due to chronograph error, probably around 3140 fps.
Group size: 2.141", not counting the flier.

43.0 grains IMR 4166:

Average velocity: 3185 fps
Standard deviation: 35 fps
Group size: 1.928", not counting the flier

43.5 grains IMR 4166:

Average velocity: 3220 fps
Standard deviation: 31 fps
Group size: 1.873", not counting the high flier

44.0 grains IMR 4166:

Average velocity: 3239 fps
Standard deviation: 11 fps
Group size: 2.285"

44.5 grains IMR 4166:

Average velocity: 3300 fps
Standard deviation: 31 fps
Group size: 2.990"

I also loaded five rounds containing 45.0 grains of IMR 4166, but after firing the first of those rounds I determined the load was too hot. It was much more difficult to extract than the previous loads, and the primer showed signs of overpressure. The chronograph registered 3318 fps.

I think I got kind of sloppy toward the end, so the larger group sizes toward the end are probably more indicative of my shooting than the powder charge. Still, it seems my Encore prefers 43.0 to 43.5 grains.