Cast Boolit Weight Difference

[tangsight]

I know this question has been asked before. Sorry for asking everyone to repeat themselves.

I cast Lyman 457125's for my '74 Pedersoli Sharps in 30 to 1 pure lead to tin. My rate is about 30 boolits per hour; a typical session is two hours of actual casting. When I weigh them, I get about a four grain spread. Aren't I supposed to be closer than that? I use a Lee ladle only pot, a Rowell #2 ladle, and the melt is kept at 750 degrees with a PID controller. The lead and tin all comes from Rotometals. The sprue turns frosty after about five seconds; I wait 25 seconds so as not to tear the base, then I tap the sprue cutter timidly with a leather mallet to cut the sprue. The boolits shoot fine, it just takes what seems like decades to cast a decent number of them that are the same weight. Of the sixty, I had five, five, and eight of the same weight to a tenth.

Recommendations?

[sharpsguy]

Get rid of the Rowell ladle and get a ladle by RCBS. That will help a lot. I would also increase the melt temperature to 790 deg.

[country gent]

I cast that bullet with good results, for me its an easy casting mould. I ladle cast with a rcbs ladle. I normally cast with 2 moulds at a time. I pair the 457125 510 grn round nose with a lyman 535 postell. My alloy is 20-1. I use a gas fired pot of 100+ lbs and hold temp around 725 degrees. The only time the ladle leaves the pot is when filling the moulds.
The night before casting I scrub the moulds clean of oil with dish soap hot tap water and a tooth brush. I then lightly drag a awl scribe or ice pick thru the vent lines. Lube sprue plate alighnment pins mounting screws and hinge pins with 2 cycle motor oil. The next day when I fire the pot they go on the warming shelf to preheat. Once pot is up to temp I flux and place the ladle in the melt. letting it come up to temp. I start with the first mould and fill ladle full. pour the mould full and the rest of the ladle into the sprue hole letting the excess run back into the pot. Set it aside and repeat with second mould. Normally I make 5-8 pours and throw those bullets back in the pot with the first batch of sprues. My bullets are normally less than 1 grn variance in weight. If you go to 2 moulds pick 2 very different designs to make sorting easier.
Making the full ladle pour keeps the base molten longer allowing for better fill out and off gasing of the bullet. The scribe insures the venting is clear. I also use a 8 ounce dead blow mallet to cut sprues. I also once mould is closed tap the right hand handle on the side 2-3 light taps to fully seat the blocks closed. Brooks sight recommends this. These are very light taps. I also when closing the mould set the blocks on the edge of my paint roller pan to pre align them when closing. A piece of 3/4x 3/4 angle iron point up 6-8: long works well also.
I cast a variety of bullets from 38 cal 360grn thru 45 cal 550 grns in the above manner and get very good bullets. a lot of my moulds are 2 cavity brass moulds.
Casting may take some experimenting to find what works with a mould. always doing the same way every time means the same results.

[indian joe]

I know this question has been asked before. Sorry for asking everyone to repeat themselves.

I cast Lyman 457125's for my '74 Pedersoli Sharps in 30 to 1 pure lead to tin. My rate is about 30 boolits per hour; a typical session is two hours of actual casting. When I weigh them, I get about a four grain spread. Aren't I supposed to be closer than that? I use a Lee ladle only pot, a Rowell #2 ladle, and the melt is kept at 750 degrees with a PID controller. The lead and tin all comes from Rotometals. The sprue turns frosty after about five seconds; I wait 25 seconds so as not to tear the base, then I tap the sprue cutter timidly with a leather mallet to cut the sprue. The boolits shoot fine, it just takes what seems like decades to cast a decent number of them that are the same weight. Of the sixty, I had five, five, and eight of the same weight to a tenth.

Recommendations?

Why make life so difficult? Segregate your boolits when you weigh them - if you got a 4 grain spread - most of them will be plus or minus half a grain from centre - a couple grains either way will still see you in the ten ring at 100yards - use the outliers for plinking - next best for short range stuff - keep the best in the centre of the spread for longrange matches. Store em after weighing in a plastic box with dividers.

[tangsight]

Joe:
That's basically the procedure that I have resorted to. I want to try to close the spread so a higher percentage of my efforts result in boolits that are long range usable.

[Bent Ramrod]

How does your 4-grain weight distribution go? If, out of 60 boolits, you have 4 or 5 light ones, 2 or 3 heavy ones and the rest more or less evenly divided between the two weights in the middle, you aren’t doing all that badly, unless you can see rounded bases or lands on the castings.

I would venture a suggestion that you are casting too slowly. I don’t strain myself but I can cast about 120 boolits of that size, from a single-cavity mould, in 2 hour’s time. My casting furnace sits in a stainless steel drippings pan that I got from Goodwill. I turn the mould over as the sprue frosts over, touch the sprue to the pan’s metal edge to drain away the sprue’s heat, remove sprue and boolit, and refill again. The mould doesn’t have time to radiate heat away before more is added, but the sprue is kept from smearing or tearing.

[tangsight]

Bent:
A good trick. I have just been waiting for the sprue to fog over. I will try your way and see what happens. To answer your question about spread: I have one boolit at 514.0 and two at 518.1 and 518.4. Between those extremes, they are spread fairly evenly, never more than three of the same weight, except for the three strings of five, five, and eight, which were centered, but 0.5 grains separated one from the next.

[indian joe]

How does your 4-grain weight distribution go? If, out of 60 boolits, you have 4 or 5 light ones, 2 or 3 heavy ones and the rest more or less evenly divided between the two weights in the middle, you aren’t doing all that badly, unless you can see rounded bases or lands on the castings.

I reckon that would be the case otherwise the spread would be bigger (Joe)

I would venture a suggestion that you are casting too slowly. I don’t strain myself but I can cast about 120 boolits of that size, from a single-cavity mould, in 2 hour’s time. My casting furnace sits in a stainless steel drippings pan that I got from Goodwill. I turn the mould over as the sprue frosts over, touch the sprue to the pan’s metal edge to drain away the sprue’s heat, remove sprue and boolit, and refill again. The mould doesn’t have time to radiate heat away before more is added, but the sprue is kept from smearing or tearing.

Once the system is up and running I would expect 100 from a solid hours casting - my gear is rough by anyones standards here - cast iron pot (holds about 40 pounds) on a gas ring, dipper pour, eyeballing alloy temperature. I get about 8 grains spread on those big boolits but way better than half are in the middle (+ or - a half grain) - a couple grains either side is fine - just load em in batches and make sure what you shoot in a match is the same batch.

[tangsight]

Joe: Wilco.

[rfd]

what works for me and yields the vast majority of BACO mould bullets of 422 and 528 grains within a 1 grain spread is the following, and i typically cast 100 bullets in a tad over an hour without rushing. monitor the 1:20 or 1:30 roto-metal alloy at no more than what my thermometer (or PID) sez is 735*. i put a doubled #64 rubber band around the mould handle ends, in order to give a consistent pressure to the mould halves. ladle snout into the sprue hole at 45*, rotate slowly, lift up the snout, i make sure to unload the entire contents of the RCBS ladle into and onto the mould, to ensure the sprue area is saturated, kept hot, and allows air to escape thus decreasing voids - when i don't do this, the grain weight spread increases. some folks "dish" or channel the sprue plate, like steve brooks does.

[sharps4590]

Once everything is up to temp you should be able to cast within less than two grains with most running within a grain. RCBS is the best dipper I've used to date. From my experience consistency and technique are the two "keys".

[Gunlaker]

What Sharps4590 says is pretty much it. I use a kitchen timer to keep track of time between sprue freezing and when I cut the sprue. I cut it by hand, wearing a leather work glove rather than a mallet. Keep an eye on the temperature. I look at it after every bullet I cast to ensure it's constant. The first few well formed bullets are generally a little light. After that the remaining ones in my batches of 100 fall within +/- 0.5gr at the most. Usually tighter than that.

A couple of things to watch for. Look at the base of the bullet when you cut the sprue ( before opening the mold ). This is the best time to see if the base is perfect. If it's not perfect than adjust your technique until they are consistently perfect. Also beware of crud building up on the dipper nozzle. Putting dross into your bullets is a sure fire way to ensure big weight variation.

I also use the RCBS dippers.

Chris.

[Lead pot]

A bullet lighter then the heaviest one with out parting line flashing from a mould that is not fully closed is a bullet not properly filled.
Over a 100 bullet cast session they should not vary a 1/2 grain from heavy to the light end if your casting routine is consistent. 80% of the cast bullets should be within 2/10ths.
I can tell if a bullet will drop light by just seeing how deep the dimple shrinks on the sprue.

[John Boy]

I can tell if a bullet will drop light by just seeing how deep the dimple shrinks on the sprue.

[indian joe]

A bullet lighter then the heaviest one with out parting line flashing from a mould that is not fully closed is a bullet not properly filled.
Over a 100 bullet cast session they should not vary a 1/2 grain from heavy to the light end if your casting routine is consistent. 80% of the cast bullets should be within 2/10ths.
I can tell if a bullet will drop light by just seeing how deep the dimple shrinks on the sprue.

you can do that with a twenty dollar alloy mold?????????

[sharpsguy]

Knowing Kurt, I doubt if he has very many Lee molds. On the other hand, I would bet that he can.

[sharps4590]

I didn't want to call it that close because I didn't want to sound as if I were bragging. However, what Lead Pot said is pretty much identical to my casting sessions. When weighing the bullets you are a little surprised when one doesn't weigh within 1/2 grain, or less, of the others. After several decades of casting, if I pay strict attention to technique and temperature my "keeper" percentage runs between 85% and 90%. Seems I always start keeping bullets too soon and the first 5-10 I keep will be light and there always seems to be another very few that weigh light for no visible reason.

[Don McDowell]

The Rowell ladle is to large to cast with, it's good for pouring ingots. As has been mentioned above get a Lyman or RCBS ladle. I also concur with picking up the tempo a bit.
Also throw the first 8-10 back , they'll usually be light, or maybe not completely filled.
Here's a pretty good video on casting https://www.youtube.com/watch?v=MGJYDTKDTr8

[indian joe]

I didn't want to call it that close because I didn't want to sound as if I were bragging. However, what Lead Pot said is pretty much identical to my casting sessions. When weighing the bullets you are a little surprised when one doesn't weigh within 1/2 grain, or less, of the others. After several decades of casting, if I pay strict attention to technique and temperature my "keeper" percentage runs between 85% and 90%. Seems I always start keeping bullets too soon and the first 5-10 I keep will be light and there always seems to be another very few that weigh light for no visible reason.

Just for fun I went and checked my last lot, I brought 98 home --
This is the LEE 500-3R mold
11 = 490
44 = 403
28 = 494
15 = 495
upon closer inspection you can see the 11 light ones - slightly rounded base - you guys would have likely put those straight back in the pot - otherwise it not so bad for a rough setup and me not payin attention as much as I should - its not the 8 grain spread that I quoted previous - this is a double cavity mold too - not so shabby on Mr Lee's part either! --- previous batch with a different mold ran 502 to 505 . checking this surprised me - doin better than I thought!!!!
When I load I always load match ammo and practice ammo - I dont shoot proper long range here - just a couple 500yard matches a year and various shorter stuff from 100 to 300.
So next casting session I am gonna take as a challenge

[country gent]

It would be interesting to know where in the run those 11 light ones were poured. Your spread is right at 1% right now. As stated above over pour the mould. keeping the base hot longer. Make sure the mould is clean and up to temp. Set the mould on top of the pot while its heating up, monitor temps and maintain as close as possible. If possible order up a lymsn or better still RCBS ladle. You might want to open the spouts hole up to .200-.210 size for better faster fill. I usually ream them out to the next size to gain a smaooth surface so flow is better and dosnt stick as easily. Keep the ladle in the pot as much as possible. A hardware store stop collar on the shaft makes a stop to hook on the edge of the pot to keep it from falling in.