I am loading for a .357 blackhawk.I am casing using wheelweights and about 10% of what i was told was babbit.I have tried 2400, reddot, greendot, 700x and now I am trying bullseye.Bullet weights of 125 gr 141gr and 158 gr.It doesn't matter what powder that I have tried the gun just won't group until I get to around 80% or more of max loading.Is this and indication that my alloy is to hard and not slugging up to fit the barrell until I load with a hotter load.At max load I am getting very little leading and this is in the last inch of the barrell.It will wipe out with a patch. Please give me your advice on what could be going on with this. I'm starting to get frustrated. Jim

Iowaloha,
I am not a very experianced caster. I would suggest that 125 grain bullets are kind of light for .357 Blackhawk. I think you should try a different cast bullet weight for that gun. Another option would be to try a different lube on that bullet and go with the powders that shoot well. A 125 grain slug in a .357 Blackhawk "begs" to go supersonic in a big way.
I don't think your gun likes the load.
Cheezywan

Since you mention "slugging up", I assume you don't know what your bore diameter is. A properly sized bullet does not need to "slug up", it's already the correct size. Leading at the muzzle end indicates that the lube is failing, either not enough of it, or the wrong kind.

I suggest you determine both bore diameter and throat diameters of your Blackhawk and size the cast bullets accordingly. Ideally, the bore should be .357" to .358 and the throats should be .358" to .359". If you find these measurements exist in your gun and your lube is adequate, size the bullets .358" and your problems should go away.

I'd think your hypothesis is correct. Bullets do need to deform a little to shoot well, it seems.

Leading near the muzzle suggest a breakdown in the bullet lube, or not enough of it.

Try some straight wheelweights, and see how it goes. Don't know what you are you using for lube, but some experimentation there might not hurt, either.

What I am trying yo do is come up with a nice mild load that shoots accurately from this gun,So far nothing. Mike I tried straight wheel weights but still have to load to fairly hot for the gun to shoot anywhere near anything resembling a group.Today I shot some factory loads in 38 special and 38+p, the gun still didn't group at all.I then tried 125 gr .357 factory loads.The darn gun shoot pretty good groups.This is a new blackhawk and this was the first factory loads shot in the gun.I will slug the throats and forcing cone and barrell this week.How much larger should i size than what the gun slugs. Thanks Jim

0.001" over would be a good start.

A particular 357 revolver that I have needs bullets that are at least .002" over throat diameter to shoot it's best. I use a Lyman 155 gr. gas check design sized to .359" and also a LEE 148 gr. wadcutter design that is a tumble lube design that I shoot as cast at .360". Both of those bullets will shoot a cylinder full under 2 inches at 25 yards. The wadcutters are loaded as very mild 38 specials. With light loads, I don't think you can really have a bullet too big a diameter as long as it will chamber easily.

I've shot a lot of 357 magnum cast bullets, exlusively with linotype, a very hard alloy. All have used Unique. All have been with SAECO #358 bullet which weights 158 grains. For one gun the maximum possible charge in 5.5 grains. Anything higher and it is almost impossible to get the fired cases out of the gun. My four other 357's can handle charges pass 7.7 grains of Unique. Never knew that powder charge could be so specific to a single gun.

Though I've have occasionally gotten flamed elsewhere for this comment, I don't like wheelweights for anything but reduced loads, a 38 S&W or a 38 Spl. Sure you can harden wheelweights and then use them for high pressure stuff but if you don't want to do that wheelweights are not, I think, well suited to 357's.

If you must use wheelweights, I'd drop the charge A LOT.

wire nut,

I would tend to agree with klw on the Unique load, but I like the heavy bullet 5.5 grains should be a good place for you to start. Another powder that should shoot well for a light load is IMR 4756, whatever you use w/Unique, use 1 grain more of 4756, because it is slower burning. Both are low pressure powders.

klw,

I don't want to argue the point, but WW+10% linotype, has won the Revolver class @ the IHMSA West Coast Championships in Oregon the last 3 yrs. I have and still shoot WW+10% lino for Silhouttes IHMSA & NRA. It is accurate and has good expansion and knockdown. This mix comes out 9-10 bhn hardness without heat treating. This is the same hardness as a 20:1 lead/tin mix. If you get the bullet too hard, it will powder puff, or explode on the target.
Also flux and stir often- keep a clean mix.

Sometimes, a harder mix is needed to keep the gun from leading. Ususally if that happens I have found that it is usually an alignment thing.

For BPCRS I like pure lead/tin 30:1

No arguement, just my 2 cents worth.

Have Fun Shooting,
Jon

Bullet hardness is a funny thing. I believe Elmer Keith developed the .44 magnum using 20:1 and 10:1. BHN number is about 11 for 10:1. Not very hard. A lot of this depends on the gun's condition.

I see a lot of people get into trouble using slower powders, like 2400, which just won't burn very well in a low pressure environment. It's really best for magnum loads. I also believe a lot of people have undersize throats. cylindersmith.com (http://www.cylindersmith.com/) is one resource for clearing that up. I have also noticed a lot of revolvers with bad cylinder timing. Not just a cylinder that fails to lock up in the thumb-drag test, but in particular a cylinder bolt (lock) that doesn't align the chambers well with the bore axis. A pistolsmith can correct these issues.

The suggestions to slug the bore and chamber throats are imperative, in my view. I also have shot a bunch of the Lee Tumble Lube wadcutters through an otherwise not too impressive K-frame 38, that loves those as-cast TLs. They get half the group size of anything else I feed it, including expensive Euro-match.

Light bullets should actually be more stable for a given barrel twist than heavier long ones, all else being equal. Usually all else isn't equal. Being shorter, it is easier for a light bullet to tip, whether in the case upon seating or on its way into the forcing cone. If everything is aligned well and the shorter bullet isn't seated deeply enough to have a greater jump to the forcing cone, it should be possible to get the bullet to shoot. Wadcutters are easier to stabilize for their length because their center of pressure isn't ahead of their center of gravity, as it is in most bullet shapes. A hollow base wadcutter actually has the center of pressure behind the center of gravity, which is a naturally stable shape.

KLW,

that huge charge difference in your guns is weird. 5.5 grains of Unique should only produce about 17,000 PSI in a .357 case with a bullet that weight. It almost sounds as if the gun is somehow pinching the bullet and not letting it go. Is there any chance your cylinder has lead build-up near the throat from firing .38 Specials, or some such thing? Curious. What do your slugs read?

Nick

Wire Nut, You can have a whole myriad of things going on here, not one of which alone will be the answer.

Go with Unclenick and know where you're at with the gun. You can measure the chambers from the front of the cylinder and the throat (big and small end) from inside the frame with a caliper. The bore should be slugged to get an accurate measurement.

Leading at the muzzle is more than likely going to be a lube problem (email me: markkw@earthlink.net) unless you can see/feel some kind of mechanical problem where you're getting the leading.

Some things to keep in mind. If you size your bullet .002" over bore diameter and the chambers are running .001" under bore diameter, the bullets that started out big enough for the bore become .001" under bore diameter as soon as you fire them thus rendering any sizing operation useless.

If the cylinder is not timed properly to the bore, you should see where one side of the throat is telling you there is a problem. Yes it is most often left or right but can also be top or bottom too, so you need to look carefully and read what the gun is telling you.

Given the fact that you stated the hot .38 loads didn't shoot as well as the full throttle .357 loads, I would tend to say you have more of a chamber problem than anything. You're needing the extra pressure to obtrude the bullets enough to give the bore some grip on them. .001" too small on the chamber side can make a huge difference in what happens past the muzzle. You need to do some measuring to narrow down the possibilities or you'll spend months flying blind and probably never getting any results.

klw, WW's will work great for many loads from mild to wild. At the very best, you may be able to drive a real light weight bullet upwards of 1800 fps from a .357 revolver but that's really pushing it, most magnum loads will barely get you into the 1400 fps range which is quite slow even for cast bullets.

I'm not flaming you, just pointing out the fact that "hard cast bullets" are quite often used to compensate for other problems. Blaming the alloy is easy but in most cases, it is not the problem. The most common problem is lube failure which can be from the lube breaking down before the bullet gets out of the bore and or lube that is too hard and comes off in chunks when the bullet exits the muzzle throwing it way out of balance. The next most common problems are bullet size and or sizing operation problems, followed closely chamber / bore / throat mechanical condition issues. Less common problems come from loading and casting operations.

Thanks guy's, I finally got around to slugging the barrell and cylinder.The barrell measured at .358 by driving the slug all the way thru.I then slugged each chamber throat indiviually. 5 measured .359 and 1 measured .360. I loaded some 141 gr wadcutters sized to .3595 over 4.2 grains bullseye and finally got about a 3 inch group at 25 yds.I switched from winchester primers to federal primers and that seemed to help tighten up the groups somewhat.
I guess I was spoiled.It seems eveything that I loaded In a jacketed bullet would shoot well but when I started casting my own It has been an up hill battle.Thanks for the suggestions any any more would be greatly appreciated. Wire nut

One other problem needs to be checked for with the slug, and that is the possibility of a barrel constriction where it screws into the frame. This problem was much more common in revolvers made from the late 60’s through the early 90’s, but still shows up in guns today. A constriction of as little as half a thousandth (upwards of three thousandths has been found) can seriously affect low velocity cast bullet accuracy. This is because the bullet must obdurate by that much after passing the constriction, or blow-by and gas cutting and tipping can occur. Fast target powders will have passed through their peak pressure by the time the bullet exits the constriction, and low pressure can’t positively bump the bullet back up. This is one reason some shooters report softer bullets being more accurate in light loads.

Jacketed bullets don’t usually show the constriction problem unless the constriction is a full thousandth or more. This is because the jacket is immune to melting and splatter caused by blow-by. It is also more resistant to being deformed into a tipped position in the bore. Soft, short lead bullets are most vulnerable to tipping after a constriction.

To find this problem in any .36, before you slug the bore, cut several pieces of 1/4” or 5/16” dowel a little shorter than the cylinder, and leave one piece enough longer than the barrel to be able to grip it. Open (D.A.) or remove (S.A.) the cylinder and run an oily patch through the bore and start a pure lead slug in at the muzzle. A brass or plastic hammer is best for this; whatever else happens, you don’t want to ding the crown. Use a Magic Marker on the base of the slug to indicate its orientation with respect to the front sight. Use the hammer with a piece of dowel serving as a punch to drive the base of the slug just inside the muzzle. Now, start feeding the dowel pieces into the bore from the breech until enough of them stack up to let you push the slug back out through the muzzle. Measure the slug across all lands and record the average as your muzzle diameter.

Note: Use a thimble micrometer with a ten thousandths (http://www.use-enco.com/CGI/INSRIT?PMAKA=510-2202&PMPXNO=8915769&PARTPG=INLMK32) vernier scale (or a digital with half-ten thousandths (http://www.use-enco.com/CGI/INSRIT?PMAKA=326-1206&PMPXNO=12387498&PARTPG=INLMK32)) to make these measurements; you want to be able to tell a half a thousandth from a quarter of a thousandth of diameter difference.

Now run another oily patch through the bore to clear out splinters. Slip the slug (try saying that 10 times quickly) back into the muzzle using the orientation mark to tell you which bullet groove goes into which land? Use the long dowel to slowly push the slug down the bore. Go, maybe, one inch per second. Keep feeling for any increases in resistance, particularly near the breech end. Have your hand where it will catch the slug when it falls out. Measure the slug again. If it has gotten smaller by more than two or three ten thousandths, you should consider lapping or fire-lapping the bore. If it is smaller by five ten thousandths or more, you definitely will have to lap or fire-lap to make the gun shoot light cast bullet loads well, and you will probably see a measurable accuracy improvement with all bullets after lapping that size constriction out.

By the way, a slug that has passed through a straight bore can be dropped into your cylinder chambers to check throat size. It should fall through without interference. If it won’t, you need the cylinder reaming done. At $37 including S&H from the source in my last post, reaming isn’t outrageously expensive. If you have a muzzle constriction, that is fine for accuracy, but you will need to tap a slug into the breech end and push it back out from the muzzle before using it to test chamber size. A muzzle constriction will make it too small to be valid for the cylinder throat test.

Nick