Alloy Weight Difference

[northmn]

I just got my 38-55 Lyman mold, the one with the gas check that is listed to throw a 264 grain bullet. Cast up a bunch today and they weighed in at 287 grains. Rather surprised at the difference. 50/50 WW/lead alloy. Same stuff throws a 258 grain bullet out of my Lee 250 grain mold so it is generally a heavier bullet than the #2 standard but this was a surprise. Had another mold once that was supposed to throw out at 220 grains and the bullets came out at 240+. Others see this large a difference?


DEP

[shafer44]

some molds just cast heavy with more lead in the mix. i had to keep hardening my alloy with one mold until it cast large enough and light enough. With a 20-1 alloy, it was way heavy and undersize diameter Lyman molds are generally based on a Lyman #2 alloy for their weight and diameters.

[jimb16]

Keep in mind that the cherry used to make a mold is used for hundreds of them. The first ones cut will be slightly larger than average while the last ones cut will be smaller. Sounds like that mold was cut with a fairly new cherry.

[Wheelguns 1961]

I have a fairly new NOE mold 314-316. Straight ww it casts 119gn. 50/50 it casts 124gn.

[Grmps]

The softer/purer the lead the heavier the boolit.
Lead is much heavier than any of the additives

[Larry Gibson]

It is my experience that the Lyman listed weights with the specified alloy is "as cast"....without GC or lube. My 375449 mould gives weights with #2 alloy at 265 gr.....one gr over what Lyman says with their #2 alloy......close enough for government work....... Add another 5.5 - 6 gr (what Hornady .375 GCs weigh) plus a tudge for lube and they weigh right at the 270 gr +/- they are often said to weigh.

With COWWs +2% tin "fully dressed" the bullets run 277 gr. Cast of my own 50/50 alloy my 375449s weigh, fully dressed, 285 gr +/-.

Appears your mould is casting about right.

[northmn]

It is my experience that the Lyman listed weights with the specified alloy is "as cast"....without GC or lube. My 375449 mould gives weights with #2 alloy at 265 gr.....one gr over what Lyman says with their #2 alloy......close enough for government work....... Add another 5.5 - 6 gr (what Hornady .375 GCs weigh) plus a tudge for lube and they weigh right at the 270 gr +/- they are often said to weigh.

With COWWs +2% tin "fully dressed" the bullets run 277 gr. Cast of my own 50/50 alloy my 375449s weigh, fully dressed, 285 gr +/-.

Appears your mould is casting about right.

The weight was with GC but no lube. I am not overly concerned as much as surprised at the difference. Now to work up a load. Extra bullet weight adds recoil and is wasted on deer but we shall see if it shoots. May take a couple of days to get things together. Nice looking bullet and I use a lot of Lee molds and forgot how nice it was to use a Lyman. Lees have served me well but the Lyman dropped bullets so much nicer.

DP

[Tom Myers]

I just got my 38-55 Lyman mold, the one with the gas check that is listed to throw a 264 grain bullet. Cast up a bunch today and they weighed in at 287 grains. Rather surprised at the difference. 50/50 WW/lead alloy. Same stuff throws a 258 grain bullet out of my Lee 250 grain mold so it is generally a heavier bullet than the #2 standard but this was a surprise. Had another mold once that was supposed to throw out at 220 grains and the bullets came out at 240+. Others see this large a difference?
DEP

If the Specific Gravity of the separate alloys are known, the difference in the weight of each alloy used in the mold can be easily calculated.

Most Lyman mold specifications use the Lyman #2 alloy to specify the weight of the bullet cast from a mold.

The Precision Cast Bullet Alloy Calculator calculates the Specific Gravity of a 50/50 ~ Lead/New Wheel Weight alloy to be 11.2516 g/cc and references the Specific Gravity of Lyman #2 alloy to be 10.6829 g/cc

(click on images to enlarge)



The 50/50 New Wheel-weight/Lead alloy Specific gravity is 1.053 more dense (heavier) than the Lyman #2 alloy

11.2516 / 10.6829 = 1.053

So, in theory, a bullet cast from the Lyman moly #357296 with Lyman #2 bullet alloy should weigh 264 grains and a bullet cast from the same mold using the 50/50 alloy should weigh approximately 278 grains.

1.053 x 264 gr. = 278 gr.

Your bullets from the 50/50 alloy are weighing about 10 grains more than that.
Is it possible that your alloy contains a little more pure lead than the theoretical 50/50 alloy?

One way to be sure would be to obtain some pure Lyman #2 alloy and verify that the mold does, indeed, cast a bullet weighting 264 grains with the #2 alloy.
Another way would be to test the specific gravity of the 50/50 alloy with a balance beam scale and some distilled water.

(How to determine Specific Gravity)


Hope this helps.

[popper]

is wasted on deer? 10%? - they will never know.

[northmn]

is wasted on deer? 10%? - they will never know.

The reason I say its wasted is that the extra weight has no extra benefit. I have to use up that much more lead alloy I am getting a little short on. I am starting to get low on WW's and would rather have the extra 5 bullets or so I could have gained casting. I am not all that shook up over things, just surprised at the extra weight. As stated, by the time you add the weight of the WW and maybe consider the alloy may have been a little heavy on the lead its been explained. Deer won't know the difference and it does not hurt either.


DP