BHN vs. Pressure

[brad925]

I am just starting casting. Have melted up 280lbs. WW's and am getting ready to cast. I am wondering if i should water drop, air cool or heat treat depending on the pressures. I will be using smokless powder in my 45-70 single and using a Lee
.459-405 HB boolit. Is there a book out there with this info or a web site i can look at?

[cbrick]

Here's a starting place,

Cast Bullets For Beginner and Expert (http://www.lasc.us/IndexBrennan.htm)

Lot's of cast info here.

Cast Bullet Article Index (http://www.lasc.us/ArticleIndex.htm)

Enough reading there to keep you busy for awhile.

Rick

[Bret4207]

Look, this is a bag of worms. Let me try and make it simple.

For a 45-70 WW alloy, air cooled, should do anything you could possibly want. Bhn # is relatively unimportant. What matters is what your particular alloy does in your particular guns. We can have 3 alloys, all measuring the same Bhn and all with different characteristics. Or 3 alloys with different makeups that perform about the same. So don't sweat Bhn.

FIT IS KING WITH CAST!!! Above all else, fit matters. No lead alloy, no matter how "hard" will work if the boolit doesn't fit. Keep it simple- take a case fired with a full powered load in that gun, jacketed is fine, and see what the inside mouth diameter is. That will be the largest size you can use without neck work. Start around that size. You can always go smaller. You need a boolit that fills the throat, that fills the grooves, that fits. A well fitted boolit tends to center itself in the throat and doesnt need obturation, (swelling of the boolit from powder pressure) to make it fit. You can give it a nice gentle launch that doesn't deform the boolit you put so much work into.

Start there. Determine what your alloy wil do before you change anything. Different seating depths, lubes, sizing practices, seating practices etc. all affect the ultimate fit. Do not fall prey to the simplistic idea a "harder" boolit will fix every problem- it won't.

[cajun shooter]

The info posted by Bret is 100% correct in every way. So many casters that are getting started today are all taken in by the BHN of the alloy. Before the Internet back in the late sixties was a great time to start casting. We only had books to read and the local expert to talk to on Saturday mornings at the local gun store. I never heard the term given as David, you must mix this to come up with a BHN of 15. I was told that if I wanted a good alloy to mix this much lead with this much tin and shot or shoot straight WW'S that the ESSO station would give me for free. My first lube and size tool was a Star and the first machine that I learned to load on was a Star. I was very luckey to have such fine mentor's. Go the the LASC on this forum and read all you can by Glenn Fryxell.

[montana_charlie]

Since you plan to use smokeless powder, you want the fattest bullet that will chamber readily.
Presumably, you plan to stay within the normal 45/70 pressure limitations, so a 'soft' bullet will work just fine. In your case, that would be your w/w metal...air cooled.

The only reason (in a case like yours) that knowing the BHN would be helpful is due to the fact that w/w is so variable, any more.
Rather than trying to match BHN to pressure, you might find some value in trying to use pure lead mixed into the w/w to produce the 'same' BHN all of the time.

But, even this is a 'down the road' project. To begin, just shoot what you have.

CM

[Frank]

brad925
I am just starting casting. Have melted up 280lbs. WW's and am getting ready to cast. I am wondering if i should water drop, air cool or heat treat depending on the pressures. I will be using smokless powder in my 45-70 single and using a Lee
.459-405 HB boolit. Is there a book out there with this info or a web site i can look at?
__________________
Lean into 'er and let 'er buck!!!

Do both, water drop and air cool, and work up loads with each. Tell us what you find. I know what my 45-70's do. If the boolit gets harder, I need to add more powder to get the same groups. With softer I get more fliers.