Change of poi.

[No Powder]

I have my 50 cal. GPR shot in for 490 cast balls from a Rapine bag mold. When I shoot 490 cast balls from a Lyman dc mold, the poi is approx. 1-1/2"  lower than the Rapines group. Could a weight difference of maybe, 2 grains cause this or is there something else going on. The sprue has been removed, and all the balls have been rolled and weighed. Groups were shot at 50yds.

[waksupi]

Measure to see if one is more round than the other.

[No Powder]

Well I tried doing some measuring. These balls measured about as close as factory swaged balls, with the exception of one spot. I must explain something first. When I roll cast balls,I always keep track of where the sprue was. When I'm done rolling, I always put a small dot where the sprue was.That spot gets loaded up just as though there was still sprue  there. There, is the only place where I am detecting any difference in diameter. I wouldn't think that would be any different than if there was sprue there.

[Fyrstyk]

I have found a difference of 2-3 grains in ball weight will affect accuracy and POI.  I now weigh all the balls I cast.  For calibers 45, 36 & 32, I put back into the pot all balls that vary more than 1/2 grain from the average weight.  For the larger calibers greater than .45, I only keep the balls that are within 1.0 grain of the average weight.  I have found in my guns that a difference of 3 grains in weight has changed the point of impact as much as 3" at 50 yards.  I am not a target shooter, but 3" is a significant change when shooting at game.

[No Powder]

Well Craig ,you might be right. I never thought the gun or I could shoot well enough to tell a difference in a couple of grains difference in weight. But I might have to pay a little bit closer attention.