I'm pretty new to this stuff, and this forum has been quite helpful to me. The more I read about hardness, alloy content, and velocity, the more confused I get. I started by casting practice loads for practice in my big bores. I started with WW, casting GC 350 grainers for my 416 Rigby, and 400 grainers without GC for my 470 NE. My velocities are about 2000 fps with the 416, and 1200-1400 with the 470. With my next batch, I plan to add some monotype or linotype, which I have aquired through the classifieds here and on Ebay. My question is, about what Brinnel hardness should I be after for these loads? I don't have a tester, but can reach a fair approximation by just adjusting the ratio of metals in my mix.
Essentially, I just want to avoid trouble with fouling, and achieve reasonable accuracy. These won't be hunting loads, just fairly high volume practice.

This site has about everything you want to know about cast bullets. http://www.lasc.us/CastBulletNotes.htm

Marty, I am in same boat as you. Just getting going casting for 416 Rigby and 450/400. Where you getting leading with 416's at 2000 fps? I have fired a few cast 350gc from the Rigby and no problems so far just using WW's and a bit of tin for better mold fill. Another newb question but how do you tell when leading is happening?

I'm sure I'm getting some, but I can't tell if it would be problematic. I still have a supply of Hunter's Extreme Coppermelt, which is no longer made. I clean every session, and the patches come out clean after a half dozen or so, so I haven't worried too much.
The WW metal I've been using was out of my brother-in-law's basement, and it's old stuff. It turns out that before the early seventies, WW alloy was 8-9% antimony, much more than the 3-4% we have now, and perhaps that's why no major problems yet. That info, by the way, was in the link kindly supplied by fredj338 above. Since I am now out of that, I need to start adding some linotype/monotype to the pot.
Everything is so vague. Something's going to get left in the barrel. How do you tell if it's excessive? These higher velocities need harder metal, but how much harder? Gas checks help, but how much can velocities go up with the same alloy? Modern lubricants decrease the problem, but to what extent?
I think I'm going to start with 3-4% tin, 6-8% antimony, and just see if any problems make themselves apparant.

the lahsc site only has half the story.
for what to expect.
just google castboolits. you'll get the answers there.

I have shot a bunch of .366", .377", .416", .459" and .476" bullets made of WWs. Everything I make is gas checked. Lube is VERY important. Carnauba Red is the best I've found ... and it's reasonably priced. Made by Lar45 on this board.

Last link I have for them is: http://www.lsstuff.com/

Some on eBay now:

http://cgi.ebay.com/Carnauba-R...611819QQcmdZViewItem

I generally use AA 5744 as a propellant.

I generally use 5744 as well.For my .416 + 450-400 I use linotype for increased velocities + for mid range use a mixture of 9 lbs, of WW to 1 lb. of 50/50 roll solder. (Lyman #2 alloy).I have found the #2 alloy works well in my .375 H+H.And yes theres a wealth of good info on the castboolits forum.

Ed Harris thinks that multiplying Bhn times the number 1442 will give you the yield strength of your alloy. That is the point at which you will see leading. A gas check and a good lube, like Lars45 makes can extend that by about 25%. Too hard can cause the bullet to "skid" in the rifling and leave deposits. The record holders in the CBA (Cast Bullet Assn) generally heat treat their bullets to a desired hardness. They can get WW close to 35 Bhn.

Rich
Buff Killer

Bullet alloy hardness isn't the only key to high velocity. Lube has an active role. Also there are loading techniques that can be applied. You can't take a real hard bullet with lars lube and it shoot it out of a fast twist Swede 6.5 and get good accuracy.....unless you know what to really do.

Idahosharpshooter please explain how too hard a bullet will skip the rifling? If that's so why don't jacketed bullets do that?

Joe

easy, if you don't fit the nose to the throat it "jumps" when it starts to move.

Rich
Buff Killer

quote:

... if you don't fit the nose to the throat it "jumps" when it starts to move.

Mmmmm... I can relate to that. In driving fairly heavy bullets that closely fit the throat fairly fast, they seem to hold the rifling fine. A slightly shorter but fatter bullet takes a little bit more jump into the rifling and shears halfway through the rifling! I don't know how much of that is taking place along the lengthe of the bore but there is little or no sign of flame cutting. I would expect flame cutting to take place quite early. (No range tests done).

Well darn, here I thought it was going to be something scientific.