Minie ball weight difference

[BLakatos]

First off, let me state that I am not at the level of shooting for any of this to matter.
Having said that, I recently bought a digital scale. I weighed a number of minie balls. Most are in the 351-354 grain range but there are ones that weigh as little as 344 and as heavy as 360.
Here?s my question. With a consistent powder charge, how much of a difference would the weight of the minie make?
Thanks, Brian

[Lou Lou Lou]

Sort them by weight and shoot the batches from the bench to see how big the groups are

[bobanderson]

If your lead is not 100% pure, you could see slight weight variances. Harder lead is lighter, and slightly larger as it comes from the mould.

Drop a chunk of your lead on a concrete floor. The pure lead will make a dull thud, hard lead will ring.

If you're casting minies with a manually operated base plug, makes sure the plug is seated all the way into the mould. A slight amount of in/out movement could cause your weight differences.

Not sure how much the weight difference will affect performance in an offhand match, but we all chase consistency.

[BLakatos]

My plan is to go to the range and try them out. However, with work and other commitments, that won?t be 3 weeks. With me, I know that it won?t make a difference but I was just wondering if anyone had noticed a difference.
Brian

[Hal]

The light ones, I would throw back. Light is a good indicator of voids inside the bullet. What are the chances the void is dead on centerline of the bullet? Slim to none. The RPM of a bullet is a lot more than one might imagine. Even with our slow rates of twist and low muzzle velocities, RPM is approaching 10,000! Something out of balance spinning that fast is going to wobble all over creation. On Minies, a good place for voids to form is at the tip of the core pin. You can sometimes see a hole up inside the bullet. I cull these just by visual inspection before bothering to weigh them.

Heavy ones can sometimes be caused by the mould not being closed completely when you are casting. Usually, a spot of lead caught between the mould halves. I don't get too many heavy ones, but I throw those back too.

I normally keep +/- .5% of median weight, which is what you appear to be doing. I have seen some guys recommend +/- .5 grains, but those guys must cast better than I do. If I did that, I would toss more than I keep.

[Carolina Reb]

When lead solidifies it shrinks. Since bullets solidify from the outside inward, they often develop a void just above the base pin, which is the last place to solidify. In extreme cases, you can see the void where lead has shrunken away from the top of the base pin. This leads to inconsistent weights.

At the ranges we shoot, the main problem with these voids is that they don?t necessarily form on the bullet centerline, so light bullets tent to be out of balance bullets, which will affect accuracy.

To get consistent bullet weights the mold needs a source of liquid lead to draw from as it solidifies. The problem is that if the sprue plate and mold top aren?t hot enough the nose solidifies first, which cuts off the bullet from its supply of liquid lead. Voids and inconsistent weights are the result.

You can reduce that by keeping the sprue plate and mold top hot. I use a bottom pour pot and leave a large puddle on top of the mold at the end of each pour. This puts heat into the plate and mold top, which improves consistency. You can actually watch the puddle dimple in at the center as it feeds the cooling bullet underneath.

You will still see weight variation with this technique. But it will be a lot less.

[michael noble]

I have a lead tester, and my lead is pure (99.99%). I just started weighing my minnies and found the same results as you. My mold is a RCBS Hodgdon 576412, my average weight is 411-413 grains. I noticed that most of my first batch of molded bullets were as low as 405 grains. I have found that these minnies will have voids in the solid part of the mold. Once the mold itself has heated up, the vast majority will drop between 411-413 grains. during moments when I clear out the dross, add lead, and re-flux, I'll notice a few lighter bullets, until the mold re-heats.

I batch my minnies into goups by weight. +/- .5gr. so all weight ranges in the 411 grain range (411.0-411.9) will be in one batch and all in the 412 grain and so on. You'll find different folks use different methods, it's all personal preference. I'll also batch and keep any minnies that weigh in the 414 and 410 grain ranges. I use these for practice.

Also, I have noticed that I have a very few heaver bullets that will weigh upwards to 416 and 417 grains. I'm still not sure why unless some impurities have gotten into the lead. The jury is still out for that one.

[Kevin Tinny]

Hello, Michael:

Voids in as-cast balls, was the issue a few of us Friendship 200 yard (Gorning in the morning) ball gun shooters could not control. So, depending on ball size, in this case .690", we made moulds that cast a 1/4 ball diameter, 1/4" high projection ON the casting. It looked like a cylindrical knob on the ball. A split block squirt die swage was made with the mould cherry. The swage fit into a large base to keep it closed during swaging. Both the blocks and base had matching, non-locking tapers to allow the blocks to be easily removed. A large Dake arbor shop press was used to push the swaging pin against the projection flush with the finished ball radius. The excess top metal squirted out the bottom. With a .690" OD, 500gr pure lead finished ball, 500 balls weighed within +/- .1gr. I doubt this is needed for skirmishing. Some commercial ball producers, such as Hornady and maybe Speer, did make swaged balls in the 1980's. They were very weight uniform and helped accuracy.

If you are interested, I can provide hand drawings of the equipment, but making it involves a lot of expensive machine shop work. Please PM me a mailing address if you wish. Thanks. Oh, the stuff we did "when out hearts were filled with fire".

Apart from contamination on block mating surfaces, variations in mould handle tension, from fatigue, etc, can create a slightly larger casting that weighs higher than normal. Some may not present a readily visible parting line ridge or fins. Try measuring OD's of normal and extra heavy ones. Smiles. Edited for typo's.
Kevin Tinny

[Fred Jr]

Hi, I probably not the best one to give you advise on this but I'm going to any way!! I believe if you are just shooting at 50 and 100 yds the weight of a few grains won't make much difference. I check all my rounds to make sure there are no voids in the core by a visual look. I did weigh a bunch once and then tried them and I didn't see any difference. Maybe I was just satisfied with pretty good results but all x's. Of course pure lead is a real must! I also do not weigh every powder charge. I use a Lyman drop charger and do check about every ten or so rounds. I also use a bottom pour pot. I know a lot of folks say you can't get a good mini from that but I'm happy with my results. Maybe I'm just lazy and not very anal!! If you intend to shoot longer ranges then you would need to do all the weighing etc to get the best results. Just my 2 cents worth!!!:D

Fred Herlinger
1097V
12TH PA
50 year member

[Don Dixon]

The first assumption is that one can cast good bullets. If then:

First, carefully visually inspect your bullets for flaws and throw the bad ones back in the pot. If you then weigh the visually good bullets and place them in ordered rows by one grain increments, you should find that they form a bell curve on your table with the majority of them being about plus or minus 2 grains from the center line of the curve. Use the bullets from the high and low ends of the bell curve for practice or team matches. Use the bullets from the center of the bell curve for individual matches, keeping them in one grain groups. You will shoot a much tighter group on target. Shooting bullets without internal flaws, but having differing weights, will produce more of a column on the target than a round group. Shooting bullets with internal voids will definitely open up the group on target.

Regards,
Don Dixon
2881V

[Maillemaker]

I have come to the conclusion that the best way to get consistent weight bullets (and thus probably voidless) with hollow-cavity bullets is to ladle-pour them.

There was an article reprint by David Francis not so long ago in the Skirmish Line that talked about doing load workups and weighing bullets, and how much variation would result in how much drop at 100 yards. I can't remember the stats now.

Steve

[Hal]

I have had the same results. I once read on the CAST BOOLITS site that you get more consistent weights on anything greater than about 400 grains if you ladle pour. I tried it and have to agree. Why? I'm not sure. I suspect it has to do with tilting the mould and rotating back level while pouring.

I have three pots. Two of them, I have removed the bottom pour mechanism from because I never used it, it was in the way of ladle pouring, and it leaked. I might do the same to the third one one day, but I seldom use it, so it's not a problem right now.

[PoorJack]

While some get better results by ladle pouring, I get very consistent results with a bottom pour Lee 4/20. I've drilled out the nozzle by about .020 and run it hot. I've found the key to consistent weight is pour fast and hot with a consistent tilt on the mold. Also allow the pour to continue with a generous size sprue puddle. In every pour, you'll see that dimple described earlier as the lead cools. Don't open the mold till you see it. I also visually inspect while casting and those with obvious flaws go straight back into the pot. If the mold is at operating temp, there are usually very few of those.

With the mold at operating temp, I get a variation of about+/-.5gr. There are a very few outliers and those are culled.

One other thing I've noticed about bottom pour pots, the amount of lead in the pot can affect that quality. I keep my pot at least half full all the time. I think this variable is why some find ladle pour more consistent.

[Carolina Reb]

I also open up the nozzle on my bottom pour pots and run them hot. When they start to drip it's time to clean the pot. When you put it back together after cleaning, lap the end of the shutoff pin with valve grinding compound or JB Bore lapping compound just like you would for small engine valves. One of my pots is 30+ years old and still casting accurate bullets.

The secret of success, whether you use bottom pour or ladle, is familiarity with your equipment.

[michael noble]

What is a good operating temperature? I usually run between 750-800.

[BLakatos]

What is a good operating temperature? I usually run between 750-800.
I?ve found my mould cast best between 820 and 850. Too many voids and throw backs if less

[Kevin Tinny]

Hello:
I have best casting weight with dipper pressed against sideways sprue plate; then rotate both to fill.

Pot metal temp of at least 775F, measured with Rotometals dial immersion thermometer. Not expensive. Pot dials inaccurate. Pre-heat mould and sprue plate by slight immersion in full temp pot. Add metal after only 1# used to reduce metal temp drop and delay that cools mould. Let ladle excess flow over top of sprue plate to elim shrink below sprue plate and to keep sprue plate hot. All this and lots more proven stuff in NRA's "Cast Bullets" Handbook. Smiles.
Kevin Tinny

[PoorJack]

What is a good operating temperature? I usually run between 750-800.

I set my Lee 4/20 to wide open. Highest it will reach is a tad over 900F but when casting, it will dip to about 850F as I toss my sprues back in as part of the process.

[Hal]

I think the general consensus on castboolits.com is 100*F above the liquidus temperature of whatever alloy you are pouring. If you are not familiar with the term liquidus temperature, it is the point at which you are changing phases from solid to liquid. Essentially, your temperature will rise steadily as the solid lead warms. Then just as it begins to melt and give you that thick gooey consistency, the temperature will plateau and remain at the same temperature for a while until the lead is melted, and then the temperature will begin to rise again. That plateau is the liquidus temperature. For pure lead, I think that is in the 625-650*F range. I usually cast pure lead at 750*F and harder lead at 800*F. The hotter it is, the more it wants to oxidize and give you that nasty dross on the surface that you have to keep pushing to the side when ladle pouring. That is where the bottom pour pot has an advantage.

[Maillemaker]

I cast about 875F. I know I'm in the right range when the bullets start turning blue when they are cooling off.

Round ball you can get away with lower temps.