I just tested BHN, with a Lee tester, on some samples of my big haul of range scrap. Two tests on each of two samples came out to 12.1 each time.
Any thoughts about what velocity that should stand up to with proper fit?
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I just tested BHN, with a Lee tester, on some samples of my big haul of range scrap. Two tests on each of two samples came out to 12.1 each time.
Any thoughts about what velocity that should stand up to with proper fit?
Anything in a typical handgun. Especially if you water drop.
or not.
12 is a little harder than i use for everything up to about 1600 fps when using a plain base boolit.
sometimes i can only get 1400 before i need a gas check.
but can shove a 10-11 bhn plain base air cooled boolit out of a 44-45 revolver/levergun with 19.5 grs of 2400 with no problems.
Your gun will have to tell you from shooting it. Usually 12.5 is plenty hard if the fit is right for many applications. You should be fine to 1200-1500 fps most of the time with that hardness. You may get significantly further, but that isn't likely or common.
In the end, alot depends on what your particular gun will do.
Bullet BHN / "Minimum" Chamber Pressure For Lead Alloys (PSI)
http://www.lasc.us/CastBulletNotes.htmQuote:
The formula (from the pages of HandLoader Magazine) to determine at what pressure an alloy of given BHN will obturate the base of the bullet and seal the bore. If the bullet is too hard to obturate, gas cutting usually occurs on the base band on the non-driving side of the rifling and barrel leading is likely. Simply multiply the alloy BHN by 1,422.
Example: Alloy BHN of 12 multiplied by 1422 = 17,064. An alloy of 12 BHN should be used with a load that develops a "minimum" of 17,000 psi. Need more info on minimum / maximum alloy BHN? These Glen E. Fryxell articles explain alloy BHN in easy to understand language.
Cast Bullet Alloys And Obturation
A Few Comments On Cast Bullet Alloys <> Lubricating Cast Bullets
I have shot 30:1 alloy to just over 2000 fps with out leading out of my rifle, but the accuracy was going south. I have shot the same alloy to 1800 fps with great accuracy.
This illustrates one of the issues with incorporating too much science into casting. While Fryxell uses that number as a minimum the data accompanying the Lee Hardness Tester lists 15,536 psi. as the maximum allowable pressure for 12.1 BHN.Quote:
An alloy of 12 BHN should be used with a load that develops a "minimum" of 17,000 psi.
I thought this particular alloy would be fine in handgun rounds and probably, mild, rifle loads. That is reinforced by the comments so far. I think I'll cast some and goose them sharply out of the barrels of a couple of my handguns and see what happens.
Or, since it is chilly here at the present maybe I'll check the BHN of some of the boolits that I know don't shed lead and see where they come in on the hardness scale.
Depending on just what you do to it and the way you use it...... about anything up to 2600 fps velocity in rifles. Conventional use described on this forum does not apply though.Quote:
Originally Posted by Alan in Vermont
I'm not sure I know what that means.Quote:
Originally Posted by 45 2.1
It all depends on what "YOU" do. One could paper patch that boolit and run it at factory velocity OR one can use booster, very slow powder and buffer to do the same thing. What you probably won't manage is casting it either AC or WD and load it in front of a conventional powder charge and do the same thing.Quote:
Originally Posted by Alan in Vermont
bob i don't think he is ready for that just yet.
alan throw that pressure formula away.
the relaxation point of the powder and where it peaks along the boolits journey is going to affect things far more than the bhn formula will affect the boolit at the start.
35-k 3" away from the cylinder/rifles throat isn't gonna mush up your boolit any, its already in the barell.
When you find a hardness of an alloy, add two to the number, put two zeros on that, and you will have the approximate range you can shoot velocity wise. For example, Bn 12, 1400 fps. Pretty close rule of thumb.
I'm not the sort who can get into spending many hours tracking down one last pinch of accuracy. I have respect for those who do and I can understand just how much enjoyment can be had from tiny groups. But, for me, too much science tends to take the fun out of it.Quote:
Originally Posted by runfiverun
Now THAT is one pretty nice reference.Quote:
Originally Posted by waksupi
I spent some time yesterday checking BHN on some boolits cast from a proven alloy, COWW with 1-2% tin added. Known results indicate no leading until things got really warm. I don't have my data handy but I know it finally gave some leading with loads that the book said could have been making pretty well to 1600 fps with that little Lee 105-SWC out of a 4" bbl. pressure gun. I've got to play with that one a bit more, maybe try harder boolits in case the lead I was getting is fomr that short boolit stripping the rifling.
Anyhow, I digressed. All three of the samples I checked, two boolits with two indents each, were between 12.1 and 12.7 BHN. Nice to know the numbers for comparison purposes, now to check those same samples with a pencil test and see how that compares to the Lee results. I've got 300 lbs of a harder mix that needs testing next. That one is 300 lbs of the 21.1 indoor range lead with 16 lbs of foundry type added. I'm curious just what that will end up being.
Alan
A lot depends on the bullet design, PB, BB or GC'd. Also what kind of firearm it is fired in. For example; I can push a PB'd AC bullet of 11 - 12 BHN to 1400 -1600 fps and maintain decent accuracy out of closed breach systems (rifles and Contenders) but can only maintain reasonable accuracy to 1200 -1300 fps out of 6"+ barreled revolvers with comparable cartridges using the same bullet/load components.
With GC'd bullets you can push that 12 BHN allow to 1400-1500 fps out of magnum revolvers and upwards of 2200 - 2300 fps in some rifles with appropriate barrel twists and maintain reasonable accuracy with a little proper technique.
But then what do I know as I am one of the "conventional" crowd here..............I suspect you are too so most of the above posts and suggestions are valid.
Larry Gibson
it's nice to have an idea of what you have so you can make each batch about the same.
once you have your load and such figured out keeping the alloy near the same does have some benefits.
changing it some can help too. [i will manipulate an alloy to make a better fit to some of my guns then make up a batch just for that one gun]
i try to keep my base alloy consistent from batch to batch,i only change it as needed.
i know it's range is bout 10-12 bhn,i don't get all worked up about it other than that.
i take what it gives me for the most part and only worry about it when i need to.