casting grain spread?

[stringstretcher]

What do you find to be an average grain spread from Hi to Lo during casting? I went out this evening, set my pot up, got the mold heated and within 3 pours was getting great looking boolits. I was using my new Ranchdog....359-190RF mold and letting air cool. I am using wheel weight/tin mix close to the Lyman #2. After sitting down with a slice of pizza, my lowest grain weight came in at 190.3. My highest grain weight was 193.7. I seperated all the castings into two groups for now.....191.0 to 191.9 and 192.0 to 192.9 and put the rest in the reject bucket. I came up with a total of 72 in the 191 range and 78 in the 192.0. does this range sound reasonable or is there something I may not be/or be doing to cause the wide spread?

[Marlin Junky]

What percentage of the batch weighed over 193 grains? Were the heavy weight bullets heavily riveted? I never throw away the heavies if they pass visual inspection but my results are usually within +/- 0.25% of the average while using my ferrous molds with which I'm most comfortable.

MJ

[stringstretcher]

Actually Marlin Junky there were only about 15 that went over the 193. I just want to know if there is a "improve casting technique" that might help. I am very very pleased with the looks of all the boolits that I sorted and kept, just seeing if this is an average spread while casting.

[anachronism]

Use a ladle & cast each cavity separately, meaning pour the first cavity, refill your ladle, then fill the next cavity & so on. Empty the whole ladle over each cavity to keep the base of the bullet hot. This helps air bubbles escape & gives a nice, sharp bullet base. Make sure your pot is at full temperature when casting. Most importantly, do your alloy in large batches for consistencys sake.

[hydraulic]

I have a picture I have been wanting to post, but I've lost the notes my niece left me about how to post pictures. It's one of those 100 yd small bore targets so many of us use. I shoot 20 rounds of .30-06, prone, 03A3, whenever the weather allows, usually once or twice a week. I recently shot the best score I ever have; scored 86%, only one flyer and that was me-my elbow slipped. The bullet is the Lyman 311413. I had run off a couple hundred of them, a few days before, and went through them and picked out the one with poor fill-out in the grooves, warts and holes and wrinkles and all manner of deformities. Wound up with twenty some, and as a lark decided to load them up and see how they shot. I can't tell any difference between them and the "good" ones. I think it must be that I shoot so poorly, I can't benefit from "good" bullets, which probably aren't that good to start with.

[KYCaster]

With multi-cavity molds I think +or- 1% is very good.

+or- .25% is an accomplishment to be proud of...MJ, YOU DA MAN!!

Jerry

[runfiverun]

with my 145 gr boolits even after lubed and checked they are usually within one grain of each other.
now, if i can get the humidity up in the casting room [humidifier in winter] swamp cooler in summer.
i can increase the weight by 1 more grain on average. and the variations go down also.
this is all technique,and consistency.
how much do you think that little bump or tear on the base weighs?

[Marlin Junky]

With multi-cavity molds I think +or- 1% is very good.

+or- .25% is an accomplishment to be proud of...MJ, YOU DA MAN!!

Jerry

Jerry,
Thanks... it's all about using enough heat with the right mold.

stringstretcher,
The heavy end of your batch is less likely to contain voids unless they're just riveted versions of the lighter ones. I have no idea what your bullets look like but most wide weight variations (e.g., 3 grains for a 190 grain) is the result of fluctuating temperature or just plain not enough heat... either at the mold or in the pot or a combination of both. Nevertheless, If you're going to re-melt bullets, re-melt the light ones.

Technique is important too, but probably not solely responsible for your 3 plus grain variation.

MJ

[stringstretcher]

I am going to mix up a batch of alloy and try the ladle pouring. I was using a bottom pour furnace for the first run. I am sure I will not be able to shoot any better than the 2 grain spread either. As I continue, I am sure my technique will improve and get better consistancy...I will put some pictures up of the bullets. I did notice that a lot of them were not real crisp around the lube groves, but looked like they were frosted a little bit and rougher than the rest of the bullet.

[Bob S]

I don't have any trouble keeping them in +/- 0.2 grains from the same mould cavity once the mould and melt are up to temperature. That's based on mostly .30 cal moulds, 130 to 220 grains, dipper casting, and keeping the melt within +/- 5 degrees of the ideal temperature for that mould and alloy (recorded in notebooks) by watching the thermometer that stays in the melt. Since I have been using the thermometer (about 25 years), I don't even feel the need to check-weigh every bullet: they are that consistent.

The average weights of bullets from different cavities of Lyman/Ideal two cavity moulds differ by almost a grain, so I keep them segregated by cavity.

Yes, I have had occasional good groups and scores with "culls" and "mixed lots". However, I have never had poor groups or scores from a proven rifle with first-quality bullets segregated as to mould cavity and oriented in the chamber the same way each time. So for me, the minor inconveninece of segregating and orienting is well-worth it when the shooting "counts". Life is too short to shoot mediocre scores. YMMV ...

Resp'y,
Bob S.

[Blammer]

for several of my moulds, I'll come up with a 3-4 grain spread, most will be in the median (naturally).

Usually by close inspection I can weed out the low ones due to improper fill out.

This is with boolits from 225gr or so for my 30 cal.

[TomT]

I stopped using a digital powder scale for bullets. Being both anal and new at casting, I have more peace of mind weighing on a digital scale that does not show the grain 10ths. After inspecting the bases for fillout, 95% of the remaining .45 200g SWC are weighing 193 or 194 grains. Heavier bullets usually have fins from not closing the mold all the way, lighter bullets either have bad bases that I missed, or voids that are hidden. The less accurate scale is also much faster, giving me a readout almost as fast as I can change bullets on the platform. Still accurate enough to catch poor castings.