Spring Back

[Wayne S]

Just wondering how much spring back there might be on WW alloy on bullets sized down .002 and .004 ?
Would it depend on the origional size ,ie .435 to .431 vs .278 to .274 ??

[lwknight]

IME , the 3% SB of WWs don't give much if any springback. Still pretty dead at that low Sb.
This was for air dropped cast. I can't answer water cooled or treated.

[felix]

Springback depends on shape of boolit as well. Smaller grooves gives more springback. A boolit has to be tough to be "springback-able", not just hard. ... felix

[Marlin Hunter]

Just wondering how much spring back there might be on WW alloy on bullets sized down .002 and .004 ?
Would it depend on the origional size ,ie .435 to .431 vs .278 to .274 ??

It depends on hardness/toughness of the lead (water quenched), and the difference between the original size and the size of the die. I get about .0023 springback on my .45 boolits. I water quench and I think they are around 18 BHN. I measured them, but can't remember exactly what the hardness was.

[runfiverun]

my 454424 square lube grooved will pop back a thou when sized from 454 to 452 they come back to 453.
thats with an 2/4 mix though, and sized within 48 hrs.

[Bret4207]

Wow, interesting question. I'll bet there's a metallurgical site some where that provides that info, but I'd also bet the exact alloy has a lot to do with it.

[Shuz]

I believe there are too many variables to come to any axiom on this one! The variables as I see them are.....alloy composition, casting temperature, heat treatment, boolit design, sizing die size relationship to the boolit being sized, and well, prolly the phase of the moon!

[243winxb]

I feel its less than .001" The bullets as they drop from the mould are out of round by about .0015" or more. Had to get a correct measurement. IMO

[leftiye]

I think the springback ain't. Not the lead springing back anyway. The die stretches and makes the boolit size larger than the sizer's actual unstressed size. Harder lead, more stretch, sizes bigger.

[lwknight]

I think the springback ain't. Not the lead springing back anyway. The die stretches and makes the boolit size larger than the sizer's actual unstressed size. Harder lead, more stretch, sizes bigger.

A few days ago while casting some 8 oz. ingots of the 30% Sb aka "superhard" I spilled and splattered some on the floor as is common for anything liquid that I touch. The thin splats of the 30% were springy when I bent them. Bend it too far and it breaks but it did spring back, so I know that there is a point of aloy mix that does spring back.

I make no guess as to what ratio or amount of anything. I just know that lead is dead and high antimony leas is springy, at least to a degree.

[Edubya]

I believe there are too many variables to come to any axiom on this one! The variables as I see them are.....alloy composition, casting temperature, heat treatment, boolit design, sizing die size relationship to the boolit being sized, and well, prolly the phase of the moon!

I'm going to agree with everything Shuz said ... except the last sentence!
EW

[Sailman]

To come up with an answer as to springback, you might want to measure the sizing die opening first.

Sailman

[303Guy]

I have a sample boolit that has a flaw line on it at which point it expanded somewhat.



That reflection line is the flaw. It's like a crack that covers about half the circumference, starting and ending at the base. This boolit has been swaged and sized.

(It's lead alloy, not brass!)