onondaga
posted this
06 September 2013
http://www.castbulletassoc.org/view_user.php?id=7620>LBD:
Cast bullets matched .1-.2 grains is unnecessary for the best match shooting of cast bullets. Cast match bullets are generally matched to 1% of total weight, for a 55 gr bullet that would be a .55 gr weight span for matched bullets to fall into.
Getting closely matched cast bullets takes very consistent casting methods. The first things to work the hardest on are:
1) consistent mold and pot temp, the historically taught standard is pot 100 deg F hotter than alloy fluidus point and mold 100 deg F lower than alloy fluidus point as the ideal temperature range to target for casting
2) consistent flow rate from pot spout or ladle
3) consistent stream length from pot or ladle to sprue gate hole
4) consistent puddle size poured on top of sprue plate
5) consistent mold handle grip force
6) clean molds that close and open easily
7) not adding sprues back into pot while casting, add when pot is low with new metal
8) consistent pour till sprue cut time for a clean cut that does not elevate sprue plate
9) sprue cut timing that allows a gloved hand for opening and no hot metal smudge on sprue plate. Correct timing will not need a baton to cut sprues cleanly with no smudge.
Doing all these things to perfection will yield about a +- 1.0 grain consistency to a 55 gr cast bullet batch. Match and sort from there if you wish.
However, I believe finding a load charge sweet spot of accuracy is much clearer to see with completely unmatched by weight bullets. Unmatched bullets will help locate the sweet spot charge more graphically to see clearly and identify the sweet spot. The sweet spot should be broad enough for unmatched bullets to shoot accurately or it is likely that you really haven't found the sweet spot at all.
Incidentally, all the bullets in the 3 targets I posted above are not weight matched, but just visually checked for flaws before size/check. My sweet spot is broad and weight matched bullets do not improve group size at all for me.
Gary