Casting Science 101

[ColColt]

From what I’ve gleaned on this forum, bullet alloys and casting is an exact science. Surprises for me have been the fact that certain alloys shrink more than others with lead being the leader in shrinkage. Also, a BHN 11 bullet today may be a BHN 12 or 13 two weeks or so later. So, in this case if I want a BHN 12, best start with BHN10-11 to begin with and add more tin to a mix to keep shrinkage down as cast but then again, there goes the softer bullet I wanted in the first place. Quite daunting, this casting hobby. If you have a groove diameter you’ve checked of .356”, you want a .357-.358” bullet in the end. You could end up with a .356” bullet even with the mix you want due to shrinkage. I’ve read that lead can shrink .004-.005” and Linotype from .002-.003” depending on caliber. Being fairly new to this “science” I find it all rather confusing and not as simple as back in the days when I just cast 50/50 lead to Linotype and just sized, lubed and shot. It all makes it hard to decide not only what to use but, if you want to order a specific mold, what initial size to ask for and what alloy to specify in light of the aforementioned.

[BulletFactory]

I know. I went round and round chasing my tail since I got my first mold last october, and only got 50 rounds off without leading after a couple thousand, and wearing out a bullet puller. Then the barrel broke, and after shooting, adjusting and shooting some more, determined that my new barrel is likely the culprit, and fixing it will set me back a hundred bucks I dont have. All that for a maybe it will work, maybe not.

The important thing to remember is not to give up. There are lots of very knowledgable folks on here who really want to help. Casting works, I've seen it in my own barrel, if only once, and there are a lot of people here who manage to pull it off regularly.

[ColColt]

They say a little knowledge is dangerous. That's where I feel I am at this point. I've read too much perhaps and some things are running together. Mr. Fryxell's excellent articles are superb but in many cases, way over my head. To me, you cast a bullet today, tomorrow it should stay the same and for sure two weeks from then...not change it's hardness. I didn't follow that at all. It would be quite debilitating to case a certain alloy, let a few bullets cool and measure the BHN onlly to discover they changed in a few days. I never thought about that at all or about any shrinkage. This is all not as simple and straight forward as I once thought.

[stubshaft]

It's always a work in progress. It takes perserverance to work through the failures, and vigilance to understand what worked and why. KEEP NOTES, as you experiment with different concepts, you may need to refer back to what you've already tried.

It is not an exact science because just when you think you've got it figured out, you realize you haven't. Try different things also. Some things that are frowned upon and taken as gospel may work in your gun.

Above all, have fun it's not worth it if you don't enjoy it!

[captaint]

I don't know, fellas....Don't think I've ever seen boolits shrink even 2 thou, let alone 4 or 5. They will get a little harder after a while though. So, just estimate bhn when you cast and don't worry about it. What's the difference anyway, between bhn 11 and 13... Not noticable in my experience. Most of what I shoot in the 45's and 38's is more like bhn 10 and I've never had any issues with that leading.
Cast em around .453 and stash them for however long. Size and lube and load & shoot. Really not rocket science. Lots of fun though. enjoy Mike

[Dennis Eugene]

Yep, Captaint is correct. It is easy to over think anything and worrying about a 2 digit change in BHN will drive ya crazy for no reason. Don't think it to death it really ain't rocket science. Dennis

[MtGun44]

You are WAY overthinking this. A few BHN are very difficult to reliably measure if you have
a machine, and most do not, and do not need it.

TIP: Get some WWt metal, cast some boolits, air cooled. Size to slugged groove diam
plus .001 to .002 for pistols, perhaps +.003 for rifles. Use a 'known good' boolit
design (ask) and start with NRA 50-50 lube. You will be fine. After you have this
working, you can fiddle to your heart's content. None of the stuff you are worried about
is worth worrying about at first. You can get great results without doing all that silly stuff.

Bill

[Duckiller]

Don't make this more complicated than it needs to be. I assume that your primary goal in casting is to make reasonably accurate boolits that don't leave excessive amounts of lead in the barrel of your firearm. First step in this process is to get a properly sized boolit. Don't worry about shrinkage. Cast some boolits with a mold you like. Set aside for a week or so. Measure or shoot them. They are going to be the size that your alloy and mold casts. I small you have a problem. If right sized fine. If large run through a sizer to the size you want.
Once you have properly sized boolits you can think about hardness. The first thing you want to think about is why do you care about hardness. There are reasons to think about hardness. Just make sure yours are valid. To defend against charging paper targets, swinging plates or empty beer cans about any hardness will do. You may have other reasons why you want boolits in a specific hardness range. Remember regardless of how you achieve a specific hardness it will change over time. Heat treat, water drop, or change your alloy they all change with time. So unless you are going to shoot your boolits exactly 3 weeks after you cast them the best you can do is have them in a hardness range that you need. I have a bunch of ancient boolits that I am not sure when they were cast or what alloy was use. I lube them, size them and put gas checks on them and they do very good for plinking in a 30/30 or .30-06. If I take the time and my vision isn't too blurry they shoot good groups in the 1700fps range.
Very few on this board think we are saving money casting our own boolits, too many toys or guns to buy. What most of us do think is that we can shoot more and have fun casting our boolits. Don't get so tied up in the details that you aren't having fun. Remember buffalo hunters were grade school drop outs that cast their own boolits.
I hope the tone of this post is too harsh, it wasn't intended to be. Most everyone here is friendly, polite and helpful. If you have a question or don't understand something ask and wait, someone will either answer or ask a question about your question. Most everyone here is friendly, polite and helpful, but we all have bad days and posts.

[303Guy]

While on the other hand ... if obtaining the target hardness is an objective in itself and is fun pursuing then by all means go for it.:drinks:

To that end, you might find adding a little copper will toughen without hardening your alloy. It does seem to screw up the accepted hardening rates - like with a measuring device you can actually monitor the hardness changes over a period of hours. Water quenching versus air cooling and after a few hours there is no difference! But shoot that stuff into sand and see how the weight retention compares to copper free alloy. Well, I've had fun with it anyway.:roll:

P.S. There is a trick to dissolving copper into alloy - firstly it has to have tin in it then it has to be 'tinned' as in with solder. And don't use too much - makes for crappy castings!:???: (0.06% max - and that may be too much!)

Ummm...... nothing exact about casting. Actually, it's alchemy - and luck, or lack thereof - and a heap of intuition. I once had this beautiful alloy. It cast such nice boolits with perfect form and all that. I had another lot of real crappy alloy which cast ugly looking boolits which I used for plinking only untill I discovered what a wonderful alloy it really was and how horrid my beautiful alloy was. (The beautiful alloy had lino in it). Now I use scrap lead pipe with some plumbers solder joints added plus a tiny bit of copper - and that's for rifles. OK, I paper patch the stuff!:mrgreen:

[Bret4207]

ColColt, listen to Mtn gun and the guys. You are overthinking this. There is science to it, but since we can't control our base metal alloys mixtures exactly it's rough science at best. That's where the art comes in, making things work.

BTW- Like Capt T said, they don;t shrink .004-.005. More like .0005.

[NHlever]

Most of us are into casting because we enjoy it at one level, or another, and because it lets us shoot as much as we like to. Some get their enjoyment from having piles of shiny boolits to shoot, some like to see just how small a group they can shoot with boolits they made themselves, some like to hunt, and harvest game with boolits they made, and some like to learn as much as possible about every little thing concerning casting. Most enjoy some of all of the above, and have fun with different guns in different ways. Boolit fit is one of the larger challenges for new casters because the molds one buys don't always give us what we need, and some of the sizing sizes we need aren't readily available.......... yet. The main thing, as others have said is to have fun with it, and get some simple satisfaction from the act pouring the silver stream, and seeing those good boolits drop onto your padded surface. I would start with the more popular calibers, .30, .35, .44, and .45 in rifles, and .38/.357, .44, and .45 in handguns. Understanding the fine points of different alloys will come with time, and experience.

[cajun shooter]

I will chime in and say that y'all are doing the same thing that all newbies go through. You read the articles by Glenn Fryxell and he is a top casting person by the way but you don't have to duplicate all his articles to cast some bullets. Get you some 20-1 or WW alloy and cast away. If shooting 357 magnum then use .358 bullets. If shooting 45 Colt then try .452 if a Ruger and .454 if other maker. These are the basic steps and will have you up and shooting. There is not a person who cast that can tell the difference between a 10 BHN and a 12 BHN while shooting paper,metal, old trees or tin cans. Have some fun with your new found sport before you get into the dissecting the frog part. I agree with Mt. Gun 44 except the lube. Use the white label brand BAC, Carnauba Red for much better performance and less smoke. The lube he advised on is very workable and has been used for many moons but it does add smoke to the firing. Most all of us that are past the 50's started by using a Coleman stove and a plumbers pot to pour a few bullets at a time. I would pour and after cooling use a Lee pan lube kit and then a Lee hammer load kit. It took all afternoon for one box of 38 splecials to be completed. If someone would have ask me what BHN I was casting at I would have said What in the h--- is that. The load was three grains of Bullseye and I would grin every time one round was fired. Lighten up and enjoy yourself and welcome to fine art of casting.

[44man]

I don't think any lead alloy shrinks beyond the amount any metal does from hot to cold. Lead will shrink as it cools otherwise it will not release from a mold but it should not shrink past what a completely cold boolit ends up.
What happens is that without antimony and tin, they will not expand as they age a while.
I suppose I have cast a few million pure lead balls and muzzle loader boolits. I have some in the drawer that are over 20 years old and they measure the same as when I cast them.
Now my .476" boolits will grow to .478" but smaller boolits grow less.
You can put a boolit back into a mold and it will be a tight fit.
The cavity in a cold mold will also be larger and the same size as the boolit. I would say my mold cavity is .478" when COLD and the boolits drop at .476", then expand to fit the COLD cavity with age.
The same boolit from pure lead will stay at .476". This is because the cavity of my mold is close to .476" when hot. Maybe .4765".
Yes, cavities get smaller when hot unlike a hole in one piece of metal.
What material the mold is made from and how much metal is around the cavity in all directions affects the expansion and might be the reason some molds drop out of round boolits.

[oscarflytyer]

You are WAY overthinking this. A few BHN are very difficult to reliably measure if you have
a machine, and most do not, and do not need it.

TIP: Get some WWt metal, cast some boolits, air cooled. Size to slugged groove diam
plus .001 to .002 for pistols, perhaps +.003 for rifles. Use a 'known good' boolit
design (ask) and start with NRA 50-50 lube. You will be fine. After you have this
working, you can fiddle to your heart's content. None of the stuff you are worried about
is worth worrying about at first. You can get great results without doing all that silly stuff.

Bill

+10! Did the same thing, until I just plain took the above advice and melted and poured lead. It really isn't that hard. Long as you know the bore size and adhere to the 'just over' size for cast, it has worked great for me. 45 ACP became almost a match gun with a minor part and my cast bullets.

[Char-Gar]

A couple of thoughts..

1. Antimony is one metal that expands when cooled. Linotype if rich in this metal so the small type letters will fill out properly when cooled. So, the antimony content of bullet alloy will have a big effect on shrinkage. So, the issue is not hardness, although as the antimony increases so will the hardness. If you view hardness as the shrinkage cause you are looking at the dog from the wrong end.

2. I agree you are over thinking this. After all of the thinking, a mold and alloy will do what they do and you won't know for certain until you put a micrometer on the cold bullet. Even so there continue to be very small changes over time.

3. Choose an alloy based on how it works for a given bullet at a given velocity. Size it and forget all of the science.

[ColColt]

My sister always accuses me of having an "analytical" mind. Due partly to my engineering background, I suppose and unfortunately, that has carried over to this hobby whether it's casting or reloading. Great advice given here by all and much appreciated and well taken. As I mentioned, I came to all these conclusions possibly by reading too much too soon.

Back in the mid '70's when I first started this it was just lead and Linotype I got from working part time at a printers shop. I had access to all the Linotype I could carry home for 25 cents/pound...sometimes the supervisor would through in five pounds or so extra as they didn't use the old Kluge press much anymore. I mixed it 50/50 with lead and that's what I used in my old Lyman Model 61 ten pound furnace. I figured I was uptown as I cast away 44's and 45's.

Much of what got me to thinking about all this was several articles by Glen Fryxell. A total guru in the casting arena so I read every word and it was in the link below I got most of that info I was concerned about. Fun is the name of the game and perhaps I'm trying to make this more difficult and demanding than it is from all the comments which again, are well taken. I'm certainly not above being taught or corrected and more than welcome any shortcomings I may have so, fire away. Having spent my fair share of time in service of our great country I don't have a thin skin at all.

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

[Char-Gar]

1. Glen is very knowledgeable and anything he writes is worth the time to read and reread. He is also a great guy.

2. A 50/50 (lead and linotype) is a very good mix for autopistol, magnum sixgun and rifles loads. It is very close to Lyman No. 2 and makes a good all around alloy.

[peerlesscowboy]

I'll bet the 44s & 45s you cast back before you got sidetracked by all the minutia shot pretty good :wink:

[mpmarty]

Quit over analyzing this. Find some wheel weights, smelt into ingots, cast boolits, lube as desired, shoot them and enjoy. I use wheel weights exclusively and just to add some good ju ju I toss in some monotype every so often. How much? I don't have a clue. My boolits come out hard enough to force into a case mouth and shoot. They don't lead. They make nice holes in paper fairly close to where I point them. I have a hardness tester that is nothing more than a paperweight. I quit using it long ago. Don't worry, be happy.

[Huntducks]

I started casting back in the 60's I was 16yrs old my dad was a plumber so I used plumers lead I casted hundred of boolits in a Ideal SC 150gr WC mold all shot in a S&W md 14 all pan lubed with javelina lube back then a lb of red dot cost $1.25 a older gentleman gave me a box of WW and said mix these 50/50 with your lead your bullets will be harder.

Like others have said it aint rocket science your truely making it to hard on yourself cast boolits are cast boolits and I don't care if there is a wrinkle in some or there not as pertee as factory as long as they come out the end with reasonable accuracy:bigsmyl2:

[ColColt]

A 50/50 (lead and linotype) is a very good mix for autopistol, magnum sixgun and rifles loads. It is very close to Lyman No. 2 and makes a good all around alloy.

I want to use something a bit softer than that mix...maybe I'll try 10 pounds of lead and 8 pounds of Linotype. Most of what I shoot is less than magnum velocity, which I consider to be around 1200fps+. I got a big heart break about 30 minutes ago. I brought out my old Lyman 61 and discovered the male connections on the side had deteriorated over the years and you could push them in with your finger. I wasn't about to plug in the connector and try it out. Guess I'll have to bite the bullet and look for something else but I won't get it as cheap as this one was. Also, I don't think Lyman or anyone else makes a 10 pound furnace these days-seems they're all 20 pound. Thermostatically controlled, it cast a lot of bullets over the decades... RIP Lyman. You were a good one but, I outlived you.:-|


I'll bet the 44s & 45s you cast back before you got sidetracked by all the minutia shot pretty good

Yep-they done good I still have the molds for both the 44 and 45 (Lyman 429421 and 454424). Today I did pretty well with the GP-100 and some 158 gr SWC's. The first target was 8 gr of HS-6 and the second one 4.5 gr 231 with the same bullet(25 shots) and, I never thought if they'd obturate or not.:)

http://i180.photobucket.com/albums/x220/ColColt/Targets/_DEF3898.jpg
http://i180.photobucket.com/albums/x220/ColColt/Targets/_DEF3897.jpg

[scrapcan]

I think you should look at rebuilding you 10 lb pot. I had the same issue a few years ago. That is a heat resistant material that hold the pins for the male side of the connector, just find something else that is heat resistant to make a new plate and screw the pins through it. If the element is not dead you will be in business. Or you could wire direct, by passing the removable cord plug. You will still have the thermostat and wind the cord around uprights when storing.

The mould master pot is what I use. It is a very durable pot. You might also want to do a search related to mould master or lyman 61 pot, there are a few posts on how to rebuild and where to get parts.

And by the way it looks like your casting is paying off. Good work.

[Bret4207]

3. Choose an alloy based on how it works for a given bullet at a given velocity. Size it and forget all of the science.

My way of doing it- mix up HUGE batches of whatever alloy you have (WW for me) and learn to work with the alloy instead of trying to mix and alloy to work for what you think you need. I shoot from 500fps to over 2K fps with plain old WW. Not every gun will achieve max performance, but most come close. Then if I really want something special I can mix 10lbs using my expensive enrichment metals instead of trying to mix 150 lbs.

[BulletFactory]

I never knew you could get that kind of accuracy with cast pistol bullets.

[fecmech]

Fix the old Lyman pot, they were Saeco's I believe. They have a 1000 watt element that will keep up with 4 and 6 cavs while adding ingots. Great pots!

[HangFireW8]

From what I’ve gleaned on this forum, bullet alloys and casting is an exact science.

Glean again. :)

I thought the pressure vs 90% deformation rule was a rule, then I found out I was already violating it with impunity... same with .001" oversized, again, found out I had already violated that, and got away with it.

There are some rules of thumb that will get you far. For high velocities/pressures, use a harder alloy, for very low, softer. How much harder or softer? There are some more rules (of thumb), and the old-timers can give a good idea depending on bore condition and barrel length, but even those rules get violated with success. Sometimes.

Fit is king, undersized is usually not good for accuracy or leading.

Use a quality lube, but one man's quality is another's garbage.

There's a lot to learn here, the most important thing is that it all don't matter if your gun doesn't like it.

My most important rules are- safety first, and keep good records of everything, so I don't have to try anything unsuccessful twice.

-HF