Thursday, January 29, 2009

I've talked about cast bullets over the past while,

so I thought I’d write some basically about how/what/why on them.

Casting requires metal to melt, a way to melt it, and a mold to cast it in. Then the bullet(sometimes) has to be sized to give it an exact diameter, and lubed. The sizing can take a bullet that’s a little too-large diameter and form it to an exact smaller diameter; the lube helps keep the metal from melting or scraping off due to friction and sticking to the walls of the bore.

The metal. For what we’re talking about, lead alloy. When you’re messing with cast bullets, you’ll run into mentions of hard and soft alloys. Generally speaking, the two elements used to alloy lead are antimony and tin; the more of them(up to a point) the harder the alloy. Tin also does a wonderful thing, making the lead easier to cast. Bronze is copper with a bit of tin added, it not only makes it harder but makes it ‘flow’ better and easier to cast; it does the same with lead. A lot of people shooting black-powder cartridges use pure lead, but often add just a tiny amount of tin to make it fill the mold better for perfect bullets; not enough to harden it, but enough to help it flow. Antimony mostly adds hardness.

You can buy pure lead ingots, you can buy lead already alloyed in a certain way for casting bullets. You can buy or pick up wheel weights, you can(sometimes) find bars of linotype, and you can buy plumbers lead(pure). All of it’s useful

Dig around and you’ll find formulas(x pounds of wheelweights added to x pounds pure lead for instance) to get a particular hardness. For some things people use straight wheelweights as that’s a pretty hard alloy. The hardest alloy is linotype, a lead alloy that used to be used by newspapers to make the plates for printing(and hard to find now). Generally, a hard alloy can be pushed to higher velocity without causing lead fouling in the bore than a soft alloy. A hard is also more brittle; bullets cast of linotype can be driven to pretty high velocity, but when used for hunting have been known to break up after impact in an animal. Soft alloys can’t be pushed as fast, but tend to hold together after impact, and can often expand nicely*.

What changes the situation of choosing alloy is a little thing called a gas check. It’s a small copper cup. Bullets designed for them have a short shank on the base, you push a check onto it and when you size the bullet it crimps the check onto the base**. This protects the base from the hot propellant gas and allows a bullet of softer alloy to be driven faster without fouling the bore(in a semi-auto it also reduces the chance of fouling the gas system). That means that you can, at least up to a point, use general scrap lead for bullets with much less worry about fouling, and you can use a softer alloy for a hunting bullet.

Melting the metal. You’ve got to keep it hot enough to flow freely and fill the mold properly, but don’t want to get it too hot. You can use a camping stove, there are electric melters into which you dip a ladle to pick up and pour the lead, or you can use one of the bottom-pour melters. I’ve got one of the latter, the smaller Lee unit that holds ten pounds of lead. It’s got a thermostat so you can keep the temperature steady, you hold the mold under the spout and lift a lever to pour the metal. It beats hell out of the pot & ladle method, and I’ve been very glad I got it.

Once the metal is melted, you need to flux it. Which means to add something to it that will help cause impurities to float to the top, and help make sure the alloying elements stay in the mix. There are fluxes made specifically for this, some people put a lubed bullet in, some people use a piece of candle wax. The lubed bullet and wax produce a lot of smoke, the special fluxes generally don’t. You put it in and stir things up thoroughly for at least 30 seconds; then you can skim the impurities off the top. With things like wheel weights, a lot of people melt, flux and clean them and then cast them into an ingot mold, cleaning a bunch at a time for later use; that’s what I usually do. Also, some ingots you buy won’t fit into a melter for casting, so you’ve got to break them up somehow for use.

I’ll pass on something I read a few years ago: a guy wrote in one of the gun rags of a friend who got very good results with his cast bullets, and the subject of fluxing the lead in the melter to clean it came up. The friend didn’t; he kept a layer of cheap, unscented kitty litter on top, said it seemed to almost act as if constantly fluxing the lead. Fresh ingots could be slipped through, and about every third use, he’d skim off the layer and put on fresh. I’ve tried it, and it does seem to work pretty well.

You need a mold. Depending on the bullet size and type, you can get molds to make a single bullet, two bullets, or up to six at a time, and they're generally made of iron, steel or aluminum. Most have the bottom of the bullet at the top; some, for making sure a bullet has the most clean, precise bottom possible, fill from the nose. There’s a piece called a sprue cutter where you fill the mold. When pour lead into the mold, you want to have an excess amount on top, so as the bullet cools and contracts it can- if needed- suck in metal from the excess to fill out. That excess is called the sprue, and when it’s cooled enough you use the cutter to take it off. Usually by tapping it with a hardwood baton. Then you open the mold and dump the bullet/s out, preferably onto a padded surface as they’re still hot and somewhat soft.

Sizing/lubing. The bullets then may need to be sized and will need lube. Sizing is usually done with some type of press into which fits a die of exact diameter, most of which have a top punch that fits on the ram to avoid deforming the nose as you push the bullet down into the die. Most sizers also have a reservoir you fill with lube. When you push the bullet into the die you turn a crank to force lube through the die into the lube grooves on the bullet. Then, when you lever the bullet up, it’s done. Lee has another type, a die that screws into any standard loading press, a piece that fits into the shellholder slot to push the bullet through and a basket that catches the bullets as they come out. On this one you lube the bullet first, then place the gas check on(if used) and then put it on the ram and shove it through. Works quite well, and doesn’t cost much.

Lube ranges from the Lee Liquid Alox(very simple and works quite well within limitations) to the original Alox(soft and kind of sticky), to the newer stuff that’s hard enough that the luber has to be heated to soften it, generally much better for high-velocity loads. I’m going to stop there; if you’re interested, there’s lots of good information, online and in books, on these. I have used several. For bullets for the Webley revolver, I’ve had good results using a .45acp or .45 Colt bullet, unsized, lubed with Liquid Alox. For rifle I prefer using one of the hard lubes because A: they’re not sticky to handle and B: in summer, around here, some of the soft lubes can get pretty messy. But I’ve also used Liquid Alox on a gas-checked bullet for .303 and 7.62x54r with good results, i.e. good accuracy and no apparent fouling.

I’ll note that you don’t always have to size the bullet, but you DO need to lube it.

Once you’ve got bullets, you need loads. The Lyman handloading manual, for instance, has cast-bullet loads for most every cartridge in the book. And they have a manual that’s nothing but cast loads. Interestingly, there are some loads that work quite well over a wide range of cartridges and bullet weights. Over at Cast Boolits, there’s a set of four basic loads that cover a whole bunch of cartridges and bullet weights. I’ve mentioned using (in my guns, check it out before trying in yours) 16.0 grains of 2400 powder with 150 to 180-grain bullets in .30-06, .308, .303, 7.62x54r and 7.5x55. With a bullet that fits the bore this load gives good accuracy in all of the above with mild recoil. I first read of it I have no idea where(I’ve eaten & slept many times since then). Very Helpful Commenter had mentioned before that his standard load in military rifles is a certain Lee dipper of Unique; gave him good results in everything. I’ll post this from the Cast Boolits article:
… Four load classifications from Mattern (1932) cover all uses for the cast bullet military rifle. I worked up equivalent charges to obtain the desired velocity ranges with modern powders, which provide a sound basis for loading cast bullets in any post-1898 military rifle from 7mm to 8mm:

1. 125 grain plain based "small game/gallery" 900-1000 f.p.s., 5 grains of Bullseye or equivalent.

2. 150 grain plain based "100-yard target/small game", 1050-1250 f.p.s., 7 grains of Bullseye or equivalent.

3. 170-180 grain gas checked "200 yard target", 1500-1600 f.p.s., 16 grains of Hercules #2400 or equivalent.

4. 180-200 grain gas-checked "deer/600 yard target", 1750-1850 f.p.s., 26 grains of RL-7 or equivalent.

None of these loads are maximum when used in full-sized rifle cases such as the 30-40 Krag, .303 British, 7.65 Argentine, 7.7 Jap, 7.62x54R Russian , or 30-06. They can be used as basic load data in most modern military rifles of 7mm or larger, with a standard weight cast bullet for the caliber, such as 140-170 grains in the 7x57, 150-180 grains in the .30 calibers, and 150-190 grains in the 8mm. For bores smaller than 7mm, consult published data.

You get a chance, go read the whole piece; there’s a LOT of information there on bullets, powders, cases and loads if you’re interested in using cast bullets. Or just interested in what’s been worked out for these. If you’re not familiar with this, when he speaks of “Lyman #3118, #311008, #311359, or #311316” and such, he’s referring to the number for that bullet & mold. They’ve got a sticky here that shows ALL the Lyman bullets and their numbers; if you’ve got a slow connection like mine, it’ll take a while to load.

I’ll throw in that I’ve stuck with 2400 for most of these loads simply because it flows so nicely through a powder measure, whereas some flake powders like Unique can be more difficult to get consistent throws with.

This is by no means a complete 'Go do it' guide, just a bit of general overview. Hope it might answer some questions anybody might have about what the hell I'm talking about.

*If you read accounts of the buffalo hunters in the late 1800’s, they’ve mentioned that a shot that hit a buffalo behind one shoulder would penetrate completely, sometimes breaking the off-shoulder, and the bullet would be found flattened out against the inside of the skin. Pure lead generally; they’d save the bullets, melt them and cast new bullets.

**Some gas checks have a thick edge so it physically locks onto the shank when crimped. Others are simply a cup, held in place by friction. On the latter, it’s possible, if the base of the bullet is seated below the case neck, for them to come loose, which is a Bad Thing. If you use that type, make sure the base does not go below the case neck.

3 comments:

Anonymous said...

Just to prove that aside from being a smarty pants, sometimes I flat out commit errors. Yes, I said it. I make misteacks. I tried my tried and true Unique powder in my M1 Carbine. According to the books the velocity was fine. Unfortunately it wouldn't function the rifle making it a straight pull bolt action. It's OK though, I have an adapter cartridge so I can shoot .30 Carbine rounds in my Ruger #1 and one of my Military bolt rifles both chambered in .308 Win (7,62x51mm NATO). For loads for the carbine, it's back to 2400. Something about pressure curves and moment. Techno engineering babble. By the way the bullet I prefer for the Carbine is the Lee C309-130-R (discontinued) as cast and tumble lubed. It is a fine .30 carbine bullet, making the .30 Carbine an effective short range (50 yd.) deer rifle.

Gerry N.

Carteach0 said...

Good post, and timely.

I cast my own as well, when I'm feeling adventuresome. It's rewarding as all get out...

Firehand said...

I like it. Being able to roll your own as much as possible is really nice. And when you can use handloads made with bullets you made yourself and get good results... well, that's just a fine thing.