Bullet Weight difference from Mold

[Helka]

Good Morning all.

I tried to search this and if it's out there please reference and close this thread

First time caster, started about a month ago. I'm using COWW and SOWW. 50/50 mix to cast with. I have a MP 359-125 mold and the HP bullets are dropping at 137gn. I would like them to be close to 125. If i just use COWW alone would that net me a closer real weight?

much appreciated

[robg]

add some tin .but 137gn will shoot fine

[Helka]

Thanks, not overly concerned as my gun likes 147 currently but wouldn't mind keeping close to 130.

[quilbilly]

Several of my molds drop a little high. My 125 gr 358 mold drops at 132 and my 200 gr 451 mold drops at 215. Both shoot well with my alloy and for some purposes, I consider the extra weight a plus. Just as long as the weight is consistent and they are sized properly, no worries. The same holds true with some of my rifle boolit molds

[Helka]

ok great, thanks

[243winxb]

More antimony is needed for a lighter, harder bullet.

[earlmck]

If you go to 100% clip-on you'll only drop less than a grain in weight. You'd need to use pure linotype to get down at or below 130 grains. monotype would get you down around 125 grains but the resulting boolit would be brittle and would be wasting a lot of wonderful alloying metal.

These are cast boolits -- you need use a decent alloy for your purpose and then be happy with the weight your mold throws.

[GregLaROCHE]

Adding a lighter alloy like tin or linotype should reduce weight some. You could also try casting at a higher temperature. Casting at higher temperatures can reduce boolit diameter and I wouldn’t be surprised if it reduces weight a bit too. How much I can’t say.

[Wilderness]

Good Morning all.

I tried to search this and if it's out there please reference and close this thread

First time caster, started about a month ago. I'm using COWW and SOWW. 50/50 mix to cast with. I have a MP 359-125 mold and the HP bullets are dropping at 137gn. I would like them to be close to 125. If i just use COWW alone would that net me a closer real weight?

much appreciated

Helka - my quick calculation says that you would need about pure linotype (16% non-lead) to get 125 gns. You probably don't want to go there.

Good results should come from correct hardness rather than bullet weight per se. For a given mould, weight is just about the perfect measure of non-lead content. I do a little test cast for my various lead sources and label the ingots with the bullet weight. Once you have a weight (alloy) that performs, you can keep going back to it by blending from your labelled sources.

The soft (heavy) end of your hoard will be pretty much what you've got. The harder (lighter) end will be lino (16% non-lead) and hardball (8%).

[Helka]

Thanks for all the tips. I haven’t shot these yet. Haven’t had a chance to make it to the range. I will see how they perform and go from there.


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[Winger Ed.]

The weight for molds is calculated with a specific alloy, such as Lyman's #2 or something similar.

"our" boolits tend to come out heavier because most folks don't use quite as hard of a alloy mix as what ya see in the books.
The more and more non-Lead goodies in the alloy will make them come out lighter and harder.