Boolit spring back??

[SWANEEDB]

When or how long does it take for spring back to occur, the reason I ask is I sized some boolits last week, they came out at .3125 and I needed at least a .313 or bigger, up to .314, measured today and they were all .313, even checked at a local machine shop--yep .313, had the gent also check my calipers with his high $ one and my cheepy was right on. Hopefully someone chimes in.

[Mal Paso]

Spring back as I know it happens right after sizing but only with water dropped or hard alloys. Soft air cooled boolits don't spring back enough to notice. In 44 cal I use a .0005" smaller die for water dropped as I do for air cooled.

I have read here that some alloys grow larger over time but I haven't seen it.

[MtGun44]

Age hardening can change size slightly, from what I have read.

Bill

[GabbyM]

If you sized them the day you cast them they will grow over a time period. Seams the more tin in the alloy the more they grow IIRC. You can manipulate the process. Seams to of worked out for you since you wanted larger. If you left them sit for a few days before sizing they'd stay closer to sized diameter.

I was bit pretty hard last year. got in a hurry and loaded up almost 200 RCBS 30-180-FN on 30-30 cases. Fresh cast boolits. The noses grew over a month or so to go over .301" Both our lever gun 30-30's have tight .300" bores so now the rounds won't chamber.

[williamwaco]

I believe spring back is a myth.

I have tried valiantly with several alloys waiting as long as 9 months and I have never seen it.

I have some .38 Specials I loaded in 1972.

I have pulled those bullets and miked them and they mike exactly the same as when I loaded them and I loaded them the day after they were cast.

I am not saying it CAN"T happen. Just that I can't catch it.


.

[prs]

Me thinks a larger size sizer or no sizer is in order here. Or open the sizer up a bit to get what you want.

prs

[geargnasher]

Age hardening can change size slightly, from what I have read.

Bill

Age hardening of certain alloys can change size slightly, from my experience.

Sizing bands right after casting doesn't always kill the age-hardening effect nor does it always mitigate age growth. Growth and hardness seem to parallel each other. What I haven't been able to determine is WHAT causes some alloys to grow and some to be stable as they age. Noses will do what they want to, and I've been bitten with failure-to-chamber by close-fitting noses and sized front bands both that have grown weeks after loading. Most alloys seem to be fairly stable size-wise after a couple of months, so I wait a while before establishing seating depth, neck expander size, neck trim thickness, or even loading boolits that have been developed to fit within a half-thousandth or less in all critical dimensions.

The alloys that have grown the most for me have all been based on clip-on wheel weights and many contained additional sundry scrap such as battery cable ends, roofing lead, and old fishing sinkers.

Gear

[mroliver77]

I was thinking with prs. Why size them smaller than you want?

[SWANEEDB]

I contacted Chris (Lathesmith) and he gave me the poop on what to do to enlarge one of my dies, we'll give it a go in the morning. Good night all and thanks for all the feedback.

[45 2.1]

What I haven't been able to determine is WHAT causes some alloys to grow and some to be stable as they age. Gear

Antimony and Arsenic content....... and to a much less degree tin content in relation to those.

[Iron Mike Golf]

SWANEEDB,

1. Recommend measuring slugs and boolits with a micrometer instead of calipers.
2. Spring back is instantaneous. Like compressing a coiled spring. That's called "elastic deformation". When we size a boolit, we want a permanent change. That's called "plastic deformation". Running a boolit through a sizing die gets you a mix of both, so the actual diameter of the die needs to be a tad less than the desired boolit diameter. How much? Depends on the alloy. I don't know any formula for calculating this. When I open a sizing die, I check the resulting boolit diameter as I go along.
3. As boolits age, the crystal structure does change and that affects the boolit dimensions. Up to this point, I pretty much shoot them within a few weeks of casting. I do have some boolits on the shelf that are almost 2 years old. I guess I should break out the micrometer on them.

[ku4hx]

I've never been able to determine if spring back is real or not. Try as I might not too, I get variations in readings on just about everything I measure. I'd think the variations you're getting could be because of spring in your measuring device, temperature, surface hardness varitions, phase of the moon and etc.

Even if it's a real phenomena, I don't think I'd depend on it to always supply the added diameter I need for a given boolit.

[45 2.1]

Analysis of alloy spring back:

1) Pure lead does not spring back at all. Cast a pure lead boolit from a mold.

2) Cast a boolit out of your alloy out of the same mold and let it age for a couple of weeks.

3) Size both in the same sizer die. Measure both with a micrometer to the ten thousandth (0.0001").

4) The difference is the spring back for that alloy at that diameter.

[Larry Gibson]

Iron Mike Golf and 45 2.1 nailed it.

Larry Gibson

[lwknight]

A hard alloy will spring back instantly as it comes out of the sizer. I have no comment on age hardening growth.

This bring to mind a question though. If you size an age hardened slug, will it spring back or will you break down the molecular structure and actually cause it to shrink?

[geargnasher]

A hard alloy will spring back instantly as it comes out of the sizer. I have no comment on age hardening growth.

This bring to mind a question though. If you size an age hardened slug, will it spring back or will you break down the molecular structure and actually cause it to shrink?

Amount of springback depends on how deeply you move the metal beyond its elastic limit. Once a boolit is age-stable and not growing any more, it won't swell back up in the long term after sizing. I've never observed any boolit shrink after sizing.

Gear

[cbrick]

45 2.1 is correct and described it perfectly.

As for me, it's not something I fret over as it's not enough in practice to cause much concern. It's at best measured in ten thousands of an inch and none of my loads are going to notice plus or minus a couple of tenths.

Just as 45 2.1 said and just like age hardening or age softening (for heat treated alloy) it is dependent on the antimony percentage and the tin percentage in relation to the amount of Antimony.

RIck

[45 2.1]

As for me, it's not something I fret over as it's not enough in practice to cause much concern. RIck

What you will notice is nose growth, especially with an already tight boolit fit.......... That can cause difficult chambering with some of the alloys used by some here.

[blackthorn]

We appear to be talking about two distinctly different things here. If you take a brass case and start to squeeze the case mouth, if you are watching, you will see it begin to deform. If you then let go, you can watch the case mouth return to its original form. That is “spring-back”. Running a cast bullet through a sizer may (or may not) result in some “spring-back” (depending on the alloy) and it will be almost instant. The other condition we are talking about is actually the potential of the cast bullet to “grow” over time. Some do and some don’t, depending on the makeup of the alloy. I think we have to be careful here to not interchange what we call the two conditions, or we run the risk of confusing people (especially those of us that are new comers to this sport). Just saying.

[cbrick]

What you will notice is nose growth, especially with an already tight boolit fit.......... That can cause difficult chambering with some of the alloys used by some here.

That's possible but . . . .

That would be growth over time and is antimony percentage dependent, the topic here is spring back from sizing and not many size the nose though of course it's possible to do that. Any "spring back" from the sized portion (driving bands) if there is any as far as I can tell is insignificant at best.

Rick

[45 2.1]

Any "spring back" from the sized portion (driving bands) if there is any as far as I can tell is insignificant at best. Rick

Spring back occurs with several items involved in reloading lead boolits, not just the alloyed boolit itself. Antimony induced particle growth can influence several things including sizing spring back. The things are inter related more so than folks here realize. The example was merely one of those items.

[44man]

Larger boolits will expand more then small calibers, just more metal. I use WW metal, water drop. I run through a Lee .476" size die, put them in plastic containers. When I go to load they will measure .478". I just load and shoot them.
I made a mold for the 30-30 and can't chamber so I size the nose. I will make the nose from soft lead for deer and that should cure it.

[detox]

Yea...linotype alloy will spring back more than most other alloys. I just ran some fresh as cast .360" diameter linotype boolits thru the .357" diameter Lee sizer and they spring back to .358" diameter. I will check them again tomorrow. I may have to run thru sizer again.

Larger .45 caliber boolits (.455" as cast) using linotype alloy require a lot of force using Lee .451 diameter sizer and will spring back to .453 diameter. I have to run them back thru twice to achieve .452 diameter. I planned on using these in the 45 acp Colt, but too much effort resizing has me now using a softer #2 alloy. The softer #2 is much easier and requires only one step thru the .451 diameter sizer.

Larger diameter "linotype" boolits .357 and larger should not be resized in the RCBS or Lyman sizer, because of the excessive force needed to resize. Especially if sizing down .002" or more. Softer alloys require less force and work just fine in these type sizers.

I have ran my linotype boolits first thru the press mounted Lee sizer then secondly thru the RCBS lube sizer just to lube.