Undersized bullets after sizing

[DanOH]

I have a STAR sizer and 1 sizing die .451.
I have used it for lube/sizing 45 lee rnfp200's and the sized diameter was .451 on the nose.
Yesterday I ran about 100 H&G 68(Miha's) through the sizer and they all came out .450..? I just stopped. These boolits drop at .453.
I cast them Friday night out of ww/counterweight lead.
Is this an alloy issue? Temp issue? I did preheat the star with an old iron that I sorta let get a little warm--(liquid lars C-Red) but even after it cooled to a more reasonable temp they cast undrsize.
Is a bigger die the only fix?

scratching my head here....

Dan

[oneokie]

Were both pots of alloy identical? For the Lee's and the 68 clones? Sounds like the alloy for the 68 clones is softer---less spring back.

[DanOH]

No, different mix. Was using a mix of ww's and lead counterweight I bought here from Willbird.

Think if I do a heat treat on them the diameter will change after sizing?

[243winxb]

from Lymans FAQ
Q: I have run my bullets through the sizing die, however they do not come out at the expected diameter. These were cast in wheelweights, would that make a difference?
A: Yes, bullets cast in pure lead or wheelweights will come out smaller, bullets cast in linotype will come out larger. This is due to the spring-back of the bullets being sized. The sizing dies are made to produce the diameters using #2 alloy.

[243winxb]

Think if I do a heat treat on them the diameter will change after sizing? I am new to heat treating/water dropping, but i did not see a change in diameter between air coolling and water dropping when casting with the same alloy.
Is a bigger die the only fix? Yes, i think you will have to purchase a new larger sizing die.

[anachronism]

No, different mix. Was using a mix of ww's and lead counterweight I bought here from Willbird.

Think if I do a heat treat on them the diameter will change after sizing?

No. They will not change. The higher the percentage of pure lead in your alloy, the smaller the bullets. Lyman "standardized" #2 alloy for this reason. Lyman moulds are cut, intended for use with #2 alloy, so they will be consistent in size & weight to Lymans specifications. Since I've seen so many wadcutter moulds that cast oversize with #2 alloy, I wonder if wadcutter moulds were held to different dimensions for use with softer, pure lead. Almost every Lyman wadcutter mould I've had dropped .360 or larger bullets with #2, or wheelweights. RCBS moulds are cut for use with linotype, as are SAECO (I believe).

[DanOH]

Ok, so is tin the active ingredient to achieve "springback" after sizing?
I didn't think to add any because they were filling out so nice and thats what I thought tin was all about.
How about if I wait a week or so, would that help the boolits resist springback?

[oneokie]

Tin is not the active ingredient to achieve springback. Antimony and Arsenic are the ingredients for hardening lead and enabling heat treat hardening.
Non water quenched boolits will age harden. 2 weeks to a month, depending on the alloy.

[Firebricker]

If your the alloy your using is giving good results I'd consider just having lathesmith make you
a die a little bigger. You can never have to many sizing dies LOL. FB

[geargnasher]

I know this wasn't your question, but are you sure you want to size them .451"? Not trying to assume too much in your case but most 45s have groove diameters around .451", some .45 Colts are .454" and sizing them to just .451" is a sure recipe for leading. Slug your bores if you haven't already and try at least .001" over groove diameter, even if you have to buy a new die for your sizer.

Also +1 on what Firebricker said.

Gear

[243winxb]

These boolits drop at .453". You just need to buy a new bigger sizing die

[DanOH]

OK...I'll give these boolits a few weeks to harden then see what happens when I size them.
DANG! I was hoping to shoot these right away.
Maybe I can fire up the pot and sweeten the mix with some lino...or water drop straight ww.
Or maybe just tumble some w/jpw.
Gettn too warm to be casting boolits, I hate swatting mosquitos with a hot mold in my hand!

[Down South]

I would think that you could lap .001” out of the die easily instead of buying a new die.

[Pat I.]

Think if I do a heat treat on them the diameter will change after sizing?

If you have a bunch cast up and there's enough WW in the mix I think if you oven treat them you'll get you're diameter back.

[Echo]

+1 for Down South. Lapping the die would take about 30 minutes while watching TV. There are instructions posted here somewhere - just make sure you measure often to keep from taking it out too much. And look to have a .452 or .4525 diameter after sizing - slabsides will like it! (Assuming you have slugged your bore...)

[DanOH]

I have some lapping compound I bought from Veral Smith years ago that is for fire lapping gun bores. Think that would be about the right grit for lapping out my sizing die? It was labled "fire lap kit" in grease pencil so I have no idea beyond that.

[cajun shooter]

If you don't have pin guages and the correct lapping tools you will be buying more than one sizing die from lathesmith