How do boolits grow?

[oldfart1956]

Fellers somethings been perplexing me for a time so I figgered I'd ask. Whenever I'm working with a new mold/different alloy or making any other changes I cast up a hundred or so, run some thru the sizer, lube some and push a couple thru the 450 and I always save about 1/4 of the run that I don't do anything with. I keep them just as a control group. All the boolits are boxed up and labeled with bhn/date cast and any other info. I got into a batch of .358's I cast over a month ago and they've been sitting on the shelf. Anyways, measured as soon as cooled to room temp they mic'd at .360. Those run thru the sizer (Lee push thru) and the 450 sized down to .358 or .359 depending on which sizer I used. And a month later...still .358/.359...no change. But, the control group which had nothing done to them now measure .362/.364 in diameter. How can they grow? How is it even possible? Audie...the befuddled Oldfart..

[44man]

Yeah, my .476" sized boolits will grow to .478". Larger boolits grow more.
A few here will have the exact answer but it is the antimony, dendrites or whatever they are called keep changing up to a point.

[shredder]

Now you have me curious. Got my mic and heading to the boolit storage area......

[Oreo]

I'd love to hear a more scientific answer too.

[winelover]

Sounds like a solution for those that constantly complain about molds casting undersized!

Winelover

[oldfart1956]

Just as a sidenote these were measured with two different mic's, a Starret and a Browne&Sharp so I don't think I gammahooched the measurements. What I'm thinking is if I knew what caused it I could figger out a way to make the boolits do this. As has been mentioned above. It'd save me a lot of time lapping out molds. Mebbe I could even get this Keith mold to shoot. GAAAH! (hate that mold) Anyways thanks for the imput guys. Audie...the Oldfart..

[Idaho Mule]

Curious minds want to know what causes this. A growing boolit could help me in a couple of my projects. JW

[243winxb]

Every time this comes up, i have to go check my test boolits in 44 caliber. They were cast on 3-1-1992 from magnum shot containing 6% antimony, then oven heat treated after sizing to .430" I started watching for a change in diameter on 3-27-2010. Boolits have been checked on 12-7-10, 2-2-11, 11-8-11, & today 2-24-13. All Boolits are still there original .430" as close is i can measure using a micrometer & vernier caliper .:-) Different Alloy = Different Results?? :confused:

[243winxb]

More http://castboolits.gunloads.com/showthread.php?105943-Changing-size-of-a-bullet-sized-and-unsize&highlight=boolits+grow and here> http://castboolits.gunloads.com/showthread.php?100367-Do-Cast-Bullets-Swell-as-they-Age&highlight=boolits+grow Lyman has said, bullets spring back after sizing. Different amounts, depending on the alloy used. They dont say how much or when??

[blackthorn]

Quote (in part) "I cast up a hundred or so, run some thru the sizer, lube some and push a couple thru the 450 and I always save about 1/4 of the run that I don't do anything with. I keep them just as a control group-------I got into a batch of .358's I cast over a month ago and they've been sitting on the shelf. Anyways, measured as soon as cooled to room temp they mic'd at .360. Those run thru the sizer (Lee push thru) and the 450 sized down to .358 or .359 depending on which sizer I used. And a month later...still .358/.359...no change. But, the control group which had nothing done to them now measure .362/.364 in diameter".

I found it interesting that bullets sized and checked later had not "grown", while those left unsized had? Does the sizing have some significance in whether they "grow" or not?

[44man]

I just checked the .30 cal boolits I made last week and I gained .0004". My .501" boolits gained .001".

[Larry Gibson]

Sizing and HTing both stop the growth as several have mentioned.

Larry Gibson

[engineer401]

I just measured some bullets I cast last summer or fall. They were not sized. They are the same size as the day I cast them. I cast them from COWW.

[btroj]

Mine grow because I add ****** to the melt. Sadly, it doesn't last very long.......

[Phoenix]

Mine grow because I add ****** to the melt. Sadly, it doesn't last very long.......

I must be being really dense today. I cannot figure out what the censored word was.

[geargnasher]

Spam filter got it. The word was a trade name for a little blue pill. Spam bots love "register" to hawk that and other such products on internet forums.

I never bothered to check heat-treated boolits, but water-quenched boolits straight from the mould often grow considerably over time. Depends on the alloy, this is why some will argue it doesn't happen and others know it does.

Gear

[Phoenix]

Spam filter got it. The word was a trade name for a little blue pill. Spam bots love "register" to hawk that and other such products on internet forums.

LOL Thanks, I thought it might be a joke but I couldn't figure it out. I went and got 3 other people and brought them in to see the sentence. None of us could figure it out.

[Phoenix]

I never bothered to check heat-treated boolits, but water-quenched boolits straight from the mould often grow considerably over time. Depends on the alloy, this is why some will argue it doesn't happen and others know it does.

Somewhere I thought I read The hardness of heat treated bullets will lessen over time. I have been reading alot about heat treating lately and have not seen the same info reiterated. Now I can't remember where I read it. I wonder id the growth has something to do with BHN change. It would make sense as the reason heat treating works if the hardness lessened it would make sense the metal would expand during the process. I am thinking it could be related but have no way to verify as I never heat treat. Altho I have been thinking about starting (heat treating is cheaper than lino.) But If it loses hardness over time I probably would not heat treat as sometimes my reloads can sit for 6 months or more.

[dverna]

Mine grow because I add ****** to the melt. Sadly, it doesn't last very long.......

If it lasts more than 4 hours you need to get to a doctor.

[runfiverun]

waterdropped boolits are just getting good at 6 months.
maybe they'll soften down in 15-20 years. [they will eventually go back to the origional alloy's bhn] if i find any in 15 years i'll be sure to test them.

[Phoenix]

waterdropped boolits are just getting good at 6 months.
maybe they'll soften down in 15-20 years. [they will eventually go back to the origional alloy's bhn] if i find any in 15 years i'll be sure to test them.

I was pretty sure they would go back, But I had no idea on the timeline. Thanks for the experience, Good to know.
Was just looking at buying an outdoor oven that can reach 600 degrees (I know i shoudnt need it that high, didnt want to get something that said 500 as that would be close to where I need it) The issue was regulation. Most dont have thermostatic controls. After reading this I was starting to wonder if it was a good idea at all. Maybe I will just look for a used propane oven to use outside. I could use the wife's summer kitchen, but she may not like that much either.
Thanks

[geargnasher]

If it lasts more than 4 hours you need to get to a doctor.

(wiping coffee off monitor)......

Gear

[40Super]

I had a bunch of 45 that I cast up last spring, I sized some of them(.452) but they were kind of small and weren't really touching all the way around, I was going to throw them into a pot sometime but never did. I finally got a really tight .45acp barrel that slugged at .4496- .4499 so I thought to use them up. When I ran them through the die this winter they sized all the way around this time. They had grown almost .001", I haven't tested any other to know if all my bullets do but that batch did.

[Bwana]

Here is a good write up.

http://www.lasc.us/Fryxell_Book_Chapter_3_alloySelectionMetallurgy.ht m

[cbrick]

But If it loses hardness over time I probably would not heat treat as sometimes my reloads can sit for 6 months or more.


waterdropped boolits are just getting good at 6 months.
maybe they'll soften down in 15-20 years. [they will eventually go back to the origional alloy's bhn] if i find any in 15 years i'll be sure to test them.

Yep, heat treated boolits will age soften in time . . . A lot of time. I tested the BHN of oven HT RCBS 35 200 that were 30 BHN. 10 years later they were 26 BHN so yes, they age softened.

The good in 6 months statement depends on the percentage of antimony in the alloy. A 6% Sb alloy will acheive final hardness much quicker than a 2% Sb alloy.

Rick

[1Shirt]

When alloys are a by guess and by golly (and I suspect that is the case with a lot of us), growth/shrinkage etc. is probably also by guess and by golly. I don't worry about it, I just adjust, load, and shoot.
1Shirt!

[hunter64]

I have a casting book from the early 70's that was put out by the NRA and I remember that it went in depth into the size of a bullet, it's composition and a time line of why bullets will swell or shrink. If I can find it I will let you know.

"If it lasts more than 4 hours you need to get to a doctor."

If it lasts more than 30 minutes I would be calling the doctor and her cute little receptionist for an examination,lol.

[40Super]

When alloys are a by guess and by golly (and I suspect that is the case with a lot of us), growth/shrinkage etc. is probably also by guess and by golly. I don't worry about it, I just adjust, load, and shoot.
1Shirt!


I don't go by guess and by golly!! I go by "I think and hope" ! :roll: