Bullet Growth

[Snakeoil]

I am aware that bullet as-cast size with vary depending on the type of alloy used to cast the given bullet. But I'm envisioning something in the range of 0.0005 to maybe a maximum of 0.002 inch variance

I did a search here and found nothing. I'm headed to the web next for a broader search. But does anyone have a rule of thumb for alloy hardness vs as-cast size?

UPDATE: I hit Submit and then did a search on the web. Found many answers, most of which were vague. One was a reference to a page on the CBA site, but the link failed to find the page. However, on that other cast bullet site, I found a post where someone actually posted numbers. It seems antimony is the primary culprit in making bullets grow. Nobody said this, but that leads one to believe that in the absence of antimony hardness differences do not result in size differences. I'm talking phyical dimensions of primarily diameter here and not weight, which could be altered by alloy density. I'm also feeling a bit proud in that my guesstimate at how much a bullet might be able to expand lined right up with the reply from a member named Shiloh (for those who might know him. I don't). He actually said "0.0005 to 0.001 inch with a max of about 0.002 inch for increase in antimony.".

So, this also makes me think that the comments I hear from others that harder bullets tend to be bigger is not 100% true if that hardness is driven by adding tin and there being no antimony in the alloy. That's kinda of a question more than a statement.

Thanks.

 

[Rick]

The percentage of Sb will determine the amount of growth, Sn to a much lesser degree. I tracked this several years ago and never found there to be enough growth to fret over. Kind of like age softening of heat treated bullets, I had a box of RCBS 35 200 bullets heat treated to 30 BHN, CWW +2% Sn, in 10 yeras they were still 26 BHN.

 

[JonB]

I have witnessed age growth of 45 cal pistol bullets, that were cast with a antimony content over 3% and maybe as high as 5%, growth in a couple years was between .0010" and .0020"
.
I've also found that a alloy with a 5% antimony content will cast a little larger at the time cast (not aged), compared to a alloy with a low antimony content, probably no more than .0005" ...especially if you keep the mold temp as cool as possible, but still not get wrinkles. Bullets will be shiny, instead of frosty.
.
I think there may be other factors involved, like how the bullet was cooled after it was poured/dumped. Because, I have had high antimony bullets that are years old and haven't grown. With that said, I suspect the growth, when it happens. won't be the same with different diameter bullets, I suspect a smaller bullet may grow .0005" and a larger bullet may grow .0010"
.
that's my 2¢ worth of guestamation.

 

[fiver]

about .001 or a little more has happened to me before.
copper can also have an effect on it happening since it forms a boundary layer around the antimony.

 

[Ian]

I had a batch from theatre curtain weights that was about like straight clip weights except cartridges wouldn't chamber after sitting a month. Cost me a range trip once. No idea what was in the alloy but .45s would grow about .002" after casting and hardening-out for a few weeks.

How much does each percentage of each constituent of a ternary alloy reduce the foundational shrinkage characteristic of pure lead? I dunno, bur the closer to equal tin and antimony are by weight percentage, the more stable and predictable the size and toughness. That said, some of the most magical alloy I've used was fussy, incredibly process-sensitive, and wildly dynamic.

 

[Snakeoil]

Okay. This question was driven by finding GC shanks on my shooting partners bullets to be about 0.010" oversize. I have no idea what the content of his alloy is. I know he got a bunch of scrap lead from another guy at the club. Since I've never really looked at this facet of casting, I needed to ground myself. As I mentioned in my opening post, I would not have expected a huge amount of size change, but I also know that you don't know what you don't know and I've been bitten in the past by applying known facts about one thing to another thing and been completely wrong.

Thanks for the input, guys. Steve called Redding yesterday and they said to send the mold back and they would take a look at it and respond accordingly.

 

[RBHarter]

1/100 over is the next cal in many cases. I don't know how a guy would even get a check on that . It could be done across 6.5,270,7mm , even then from 6.5 to 7mm is a long jump .

 

[JonB]

Sometimes you can have a GC made to a custom thickness, to fit a out of spec mold...BUT .010 oversize is a lot. I hope Redding can help your friend out.

 

[Tomme boy]

I have run into this several times for different rifles. Like Ian it has cost me several range trips as they would not chamber. Every time it was lino type and range lead mix.

 

[fiver]

sucks hind teat on opening morning when your miles away from home at sunrise.

 

[RicinYakima]

sucks hind teat on opening morning when your miles away from home at sunrise.

Didn't practice enough!!!!

 

[fiver]

same box of ammo from the same lot,, it just sat around since the year before.
they were a 'tight' fit to begin with [the nose engraved when chambered] and that little bit of time was just enough to require too much extra effort to chamber the round.
fortunately it was crimped and come back out... especially since i stopped before i rammed the round home.

i was able to fix the situation with a little lip balm and move on with my day, but any more and it could have been a drive back to the house.

 

[burbank.jung]

I cast 38148wc, PC'd it and seating it was slightly tighter than sized first. But, I took the same bullets that were not resized and bagged them about 8 months ago. Without resizing them, I tried seating those bullets and.. jeez, it was tight. I sized the bullets from the bag and seating them was as easy as seating the initially fresh resized bullets.

 

[Bigbore5]

I cast then use a push through sizer, seating the checks beforehand with the 450 with the check seater in it if used. Then age for about two months. Before loading, they get lubed and sized again with the 450. Never a problem even with tight fitting driving band bullets.