Lee 310 44 cal dropping really light

[MoP_GBB]

Long time lurker, have been casting for a few years, but in relation to the experience level of most of ya'll ... I'm a noob. With that said ...

Picked up a Lee 310 gr, 6 cavity .430 mold. Used Lyman #2 straight from Rotometals. Poured at what my RCBS thermo said was 700'ish.

Here is the data:
n=73 (projectiles)
Mean weight in grains: 288.2
Heaviest projectile: 290.7
Lightest projectile: 285.9
Hi Lo Range of: 4.8 grains (variance)

a 310 grain mold throwing casts 21.8 gr's light on average seems to be a problem, no?

These same projectiles, gas checked and lubed (pan lubed):
Mean weight in grains: 296.8
Heaviest projectile: 299.2
Lightest projectile: 294.2
Hi Lo Range of: 5 grains (variance)

Love to hear your thoughts and guidance. Until proven differently, I'm under the belief that this is way more likely something I did, than a problem with the tools.

[trapper9260]

It sounds like your alloy mix will give the weight you get . Welcome to the site . I have the same mold and I go by what I want for my mix then the weight. It works for me .

[bmortell]

#2 is 10% things that arent lead and are lighter. so that would seem normal to me.

if you wanted them to be heavy for whatever reason 50-50 WW/pure is dense and fairly hard if heat treated /water dropped.

[fredj338]

Every manuf sets their mold weights with a certain alloy. I am not sure Lee uses #2. It is also possible your #2 is actually a bit harder than #2. I wouldnt sweat it though.

[megasupermagnum]

That doesn't sound far off at all. I'd have to double check, but cast of clip on wheel weight plus tin, mine come out pretty close to 310 grains when lubed and checked. Lyman #2 should be lighter.

[Four-Sixty]

268220

Here are some I cast. The frosty bullet (left) is 3 grains lighter (304 versus 307 grains) than the other bullet. The frosty bullet was cast when the mold was too hot.

Another factor that may be introducing variance is the fill of your mold. I would compare your heaviest bullet to that of your lightest bullet. Take a look at the bottom edge of the base. Does the heavier bullet have a shaper edge on the base, and the lighter bullet more of a rounded one? If so, your heavier bullet has a better fill, and more material present - hence the difference in weight.

[mdi]

Every manuf sets their mold weights with a certain alloy. I am not sure Lee uses #2. It is also possible your #2 is actually a bit harder than #2. I wouldnt sweat it though.

Agree with Fred^. Your alloy and your temps/methods are probably different than what the mold designers used...

[MoP_GBB]

Ok, perfect, thank you guys. Super helpful and I seriously appreciate the feedback!!!