38 spl. Lead swc 158 or 164 gr.

[Glockmeister19xc]

I normally load plated bullets but recently picked up a good amount of lead hand labeled 158 gr. Already lined ready to load however on the scale they weigh in at 164 gr. , is this normal, can the lead mixture vary the end results from the mold or does the lube weigh the difference or do I just find load data near that weight and go from there. ?? Thanks joe

 

[Mobuck]

Antimony and tin are lighter than lead. If the mold was designed to produce 158 grain bullets cast with antimony/tin as a hardener and pure lead is cast, the bullets will be heavier. Six grains heavier? Molds (especially older ones) are a "relative thing" and cast bullet weights are variable.
I'd guess your bullets may be fairly soft so load accordingly and/or expect leading.

 

[David R]

Don't bet on the leading because the lead MAY be soft. Its a 38. No high pressure or velocity. Hornady and Speer make swaged bullets out of pure lead. Soft as can be, and they do not lead as long as they fit the gun. Hornady Hollow base wadcutter are the most accurate bullet out of my 38 and they don't lead.

Size of the bullet , cylinders and bore make the big difference. Load some and shoot them. See how they work. I have shot Tens of thousands of home cast bullets.

David
Load them and shoot them.

 

[Charlie98]

Hornady Hollow base wadcutter are the most accurate bullet out of my 38 and they don't lead.

I bought a box of those many years ago... they were gawdaful messy to load, but boy howdy would they shoot!

OP, as long as you are not pushing a maximum charge of powder, I wouldn't worry too much, and I don't suggest pushing soft cast to maximums, anyway.

 

[Unclenick]

I don't think those are pure lead. I read somewhere they put a couple of percent antimony in the alloy. Not as hard as cast but not as soft as pure lead.

They don't necessarily lead a bore. The condition of the bore and the sizing are key. With a revolver, I usually find the least leading with bullets 0.002" over groove diameter rather than the usual 0.001" over groove, assuming that fits the chamber throats well.

OP, try weighing a number of the bullets. For target shooting with a revolver, I try to keep them within about 3 grains of each other. In this case, though, you are looking to see if the caster wasn't getting the mold closed completely due to debris. You are also looking to see if you can detect different weights of roughly equal quantity, indicating which cavity threw which ones, so you can sort them by mold cavity to identify the most accurate ones.