Does different bullet weight matter ?

[vrh]

I am currently loading cast bullets for my .243 rifle. The finished bullet ( sized, gas checked, P.C. ) weighs 101 grains. I weigh each bullet and separate each bullet into groups. Example- 101.1 grains , 101.2 gr , 101.3 grains etc.
My question is how much difference can I expect from groups fired at 100 yds. shooting 101.1 grain bullets versus say shooting 101.9 grains ? Or does it matter if one just shoots the 101 grain bullet w/o weighing each into it's own group?
Was wondering who has done this and what benefits if any were found to improve groups. I only shoot at targets for fun, but still would be nice to stay in a 3 inch bulls eye at 100 yds.
Thanks for everyone's response.
Vearl

[Wayne Smith]

How straight your boolit enters the rifling (run-out) probably has more to do with the accuracy than one tenth of the boolit weight difference. Only way to find out is shoot them in your rifle and let us know the results.

[44man]

You won't see any difference. I gave up weighing long ago, I actually shot worse. Wayne says it good.
Maybe with .22's.

[GhostHawk]

Like 44man I gave up weighing years back.

I will say that it might be something to consider for the smaller/faster calibers. .223, .243 a tenth of a grain will have more impact on flight than for say a .45-70 shooting a 500 grain boolit.

I think that the larger calibers are a lot more forgiving in many respects for cast than the small fast calibers are.

[georgerkahn]

I "90%" agree with other respondents to your query. However, a void (e.g., miniscule air bubble) in a boolit will surely wreak havoc in its flight from muzzle to intended target! For *ME*, I treat it is a "quality control" issue. To wit, several tenths of a grain will not have much affect -- as other who replied correctly noted, but I have had cast bullets which never made it to target by flying apart en route, as well as those landing quite a distance from intended zero (shot from a rest).
I have an old, surplus pan balance, and after zeroing a cast bullet on it, check subsequent ones, using the speed of pan movement as my "whoa -- check it out!" criterion. After you do a few, you can see the pan slowly drop for a, say, +.2gr bullet; or, conversely rise for one similarly lighter. HOWEVER, any more than a grain or two in weight from zero's will move the pan quickly enough to make said slug suspect. And, 99% or so of the time, so it is.
Mind you, this is neither scientific nor anything I've ever read or heard doing -- but, it works for me. I use electric-powered bottom pour furnaces, and an interesting note is I seem to experience less weight differences in the almost-full RCBS Pro-Melt than I had in my old Lyman Mould-Master -- BOTH, PID temperature controlled.
In talking with fellow local casters, where many are "died in the wool" ladle casters, and they all seem to believe they have less weight variation than I do -- due to the bottom pour's nozzle. ???? I do not know... However, I read your inquiry and reckoned I'd let you know what I do.
BEST!
georgerkahn

[44man]

Yes, I am one of the OLD ladle casters too. I don't get voids that are death to accuracy. Even the wrong lube will throw a boolit out if a speck is left in a groove. I have recovered boolits on the range with half the grooves still full.
A lube that runs out long before exit is also bad. SPG did that in my BPCR, last 10" was fouled badly and the boolit has to fight it or run fouling over. Seen it with TL moose snot too. Fouling damaged boolits are not much better then gas cut.

[nagantguy]

I agree with what people said above to the op's question and I'll add my own experiment; two years ago I did a total rehab rebuild of a late 1930s 1894 found laying on a basement floor, gun sock rotted into the wood. It all turned out very well, the action and barrel were packed with grease so the bore is very shiny and smooth. Played with several molds, different boolit styles and store bought jwords, after casting several hundred different boolits found one that clearly shot better than the others though everything shot well in the 170 to 181 weight range loaded up everything with same powder ladder style 22-26 grains different weights different profiles different brass and shot all of the "experimental " loads at a paper plate at 100 yards, the resulting group was a lateral pattern about 3 inches long about 1.5 inches wide just about centered on the plate, 4 grain powder charge difference and 20 grain boolit weight difference and all of it didn't seem to matter much as every shot was easily minute of whitetail.

[Scharfschuetze]

I don't weigh either; but I am pretty strict on my visual inspections.

Every now and then, particularly past a couple of hundred yards, I'll get a flyer and I'm pretty sure the boolit's center of gravity was off center due to a bubble somewhere in the projectile. I've actually watched these while spotting for other shooters (20X Leupold spotting scope) and those in-concentric boolits fly in a helix type trajectory to the target. Weighing probably would probably catch these out of kilter boolits, but it's not very often so I don't bother.

Now if I was competing at some of the more refined events, I would certainly weigh 'em. I hope to shoot this spring at the club cast boolit matches and I'll probably weigh those projectiles. I've got a PACT electronic scale that makes short work of these onerous little tasks.

[runfiverun]

in the bigger stuff I only weight sort into groups and not an individual .1group.
in my 308 rifles I sort one particular boolit because I push it faster in one rifle.
for that one I weigh into .3 groups.
and only within a 1 grain separation.
anything under the acceptable 166gr range is too light.
and anything over 166.9 is too heavy and I see it when I size as it affects the drive bands.
one tells me I didn't get enough lead in the mold or I was out of it's temperature zone.
and the other tells me I didn't close the mold properly or my alloy temp was off.

I can pretty much shoot any of the three 'in the zone' groups together and it don't matter.
the too heavy ones are gonna fly off somewhere else because of the damage to the drive band in sizing, and the light ones don't groups as well.

this is in a rifle that will shoot under 1/2" easily.
the same loads in my ruger boat paddle with the old leupold 3x9 are @ 1" or so, which is about it's best with jacketed too.

or I can just shoot the rcbs 30-165 silhouette boolit on top of 18grs of 2400 and get nearly the same results in that rifle with just a visual inspection and no fancy case prep just by lifting the muzzle before each shot.

you can probably guess which load I have at least 300 of ready to go shoot, and which one I have about 50 of at any one time.[maybe]

[hutch18414]

Since I have gotten my "consistency applied" techniques pretty well wired out I usually keep my boolits within .3 gr when casting. And even when I am having "one of those days" I am pretty much within .7 gr. And after shooting a whole bunch of them I can't tell any difference. Back when I was getting 1-2 grain differences it really made a difference. And my thanks to Goodsteel for breaking down the methodology of consistent casting into a repeatable scientific program.

[MarkP]

I will separate by cosmetics inspect at the heals as a final check; heals with nice square edges in one container the rounded less filled in another. Defects on bearing surfaces will be re-melted.

[Scharfschuetze]

I will separate by cosmetics inspect at the heals as a final check; heals with nice square edges in one container the rounded less filled in another. Defects on bearing surfaces will be re-melted.

Good advice Mark. The heel or base of the bullet should be as square as possible for good accuracy.

My nose pour Hoch mould (190 grain 30 cal) produces the best bases of any of my moulds. That is what it is designed to do and it is a real advantage to nose pour moulds.

[robg]

I shot 180 and 160gr boolits with 18 gr of 2400 they both grouped within 2 inches of the point of aim at 100 yards which is about the same size as my 20 round groups of one boolits or the other.so at that distance I don't think a grain or two make much difference,but, big but ,probably a better shot or longer range will show a huge difference.

[swheeler]

I shot 180 and 160gr boolits with 18 gr of 2400 they both grouped within 2 inches of the point of aim at 100 yards which is about the same size as my 20 round groups of one boolits or the other.so at that distance I don't think a grain or two make much difference,but, big but ,probably a better shot or longer range will show a huge difference.

Not sure this is a good comparison, a 160 gr bullet and another bullet from the same mold, cast at same time, that weighs 158 grs probably contains an internal void, the harder you push it the more it will show.