Bullet Mold Issue. Any Help is Appreciated.

[mgunner]

Several months ago I showed you all my first casting of 124 grain bullets using a Lee 6 cavity truncated cone mold. The model number is TL356-124-TC. I cast using Lyman #2 from Rotometals. I haven't been able to load them up until now and I found something a bit puzzling.The diameter is 0.356 which is correct, but the mold didn't cast 124 grain bullets. Here are 10 random bullets I weighed using an RCBS M500 scale:

120.3
119.8
118.8
119.6
119.9
119.3
120.4
119.8
119.2
120.2
120.2

Can someone tell me why these aren't weighing 124 grains? Is this common when using this mold?

 

[byron]

Several months ago I showed you all my first casting of 124 grain bullets using a Lee 6 cavity truncated cone mold. The model number is TL356-124-TC. I cast using Lyman #2 from Rotometals. I haven't been able to load them up until now and I found something a bit puzzling.The diameter is 0.356 which is correct, but the didn't cast 124 grain bullets. Here are 10 random bullets I weighed using an RCBS M500 scale:

120.3
119.8
118.8
119.6
119.9
119.3
120.4
119.8
119.2
120.2
120.2

Can someone tell me why these aren't weighing 124 grains? Is this common when using this mold?

I don't really know much about it but I have been told that temp. of your mold and lead can make a weight difference

 

[Acer-m14]

my guess ..

Lyman #2 alloy (90% Lead, 5% Tin, 5% Antimony) there is your missing 4 to 6 grains , it not pure lead ..

 

[dsdmmat]

Lee uses 1-10 tin to lead mix for their measurements

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[mgunner]

Lee uses 1-10 tin to lead mix for their measurements

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Thank you for your help. That explains it. I also looked at the instruction sheet that came with the mold and it states that their bullet weights are based on a 95/5 lead tin alloy. When I was selecting the alloy to use, I was going for something on the harder side just so I wouldn't have to deal with potential leading issues. I forgot or just missed that mention of 95/5 for this mold.

Do all bullet mold manufacturers base their bullet weights on specific alloys? If so, do they use Lyman #2?

 

[kev74]

Your bullets are more consistent than some commercial bullets I've bought.

Don't sweat the variance from the claimed bullet weight.

 

[mgunner]

Your bullets are more consistent than some commercial bullets I've bought.

Don't sweat the variance from the claimed bullet weight.

At least I learned something. I was just mystified as to what I missed or overlooked. I don't mind making mistakes, as long as I know what the mistake was so I don't make it again.

I was planning on using load data for a 124 grain bullet, but I found data for 120 grain cast bullets that I'll use instead.

 

[Tisto]

Not that this is where the weight varience is, but you ran your castings through a lube/sizer, right ? You didnt mention that.

The weight issue is certainly in the alloy. Nothing to worry about.

 

[mgunner]

Not that this is where the weight varience is, but you ran your castings through a lube/sizer, right ? You didnt mention that.

The weight issue is certainly in the alloy. Nothing to worry about.

I used liquid alox and ran them through a Lee sizing die. The bullets came out of the mold with 0.356 or 0.357 diameter. I'll put another coat of alox on and then load some up.