Question on Lead/tin ratio?

[PolarFBear]

I've melted a lot of lead over 15 years. But, it just hit me on what that ratio thing is that Keith and the Lyman book talk about. Is the ratio of lead to tin measured in volume or weight? My method has never been precise. I just plop some linotype, pewter or tin into my wheel weight melt and it's all been good. I am a plinker, not into competition in any form. I DO use pure lead for my black powders.

 

[Unclenick]

It's the percent by weight. With all the awkward shapes different alloys come in, ingot shapes, wheel weight shapes, round shot shapes, and recovered bullet shapes, there's no simple way to measure by volume unless you want to take the time to do water displacement on everything. As a general rule, chemistry uses constituent weight to mix all solid material percentages. Fluids are done by volume if their constituent percentages are already known or if they are pure, in which case their molecular weights let you calculate the mass percentages.

 

[PolarFBear]

Thanks UncleNick

Just had a "brain-fart". Spent some time sorting brass and cleaned a few shooters. Back on track now.

 

[Recycled bullet]

The ratios are to help you decide and use the bullets in a way that results in more consistent results based on it's specific physical properties like hardness, size, ductility, toughness resistance to plastic deformation etc.

If you powder coat the bullets the exact composition of the lead becomes less important. Powder coat is like an polymer jacket that gets baked on and later sized for consistent for into the brass and gun.

Different ratios are like different hammers or different golf clubs, use a specific tool for a specific job or can use a more general tool with some adaptations.

 

[Unclenick]

The powder coat makes it less important as far as barrel fouling goes because the PC provides a form of gas check, expanding into land corners and providing a phase change material shield against hot gases and an elastic shield against particulates. The old poly-wads from the '90s did the same thing. But once you get the bullet out of the muzzle, hardness will still affect expansion. In a high-power rifle load attempting to approach jacketed bullet velocities, hardness prevents slumping under the high g-forces involved (at 40,000 psi, a 180-grain .308 bullet experiences a peak acceleration of almost 116,000 g.