Brinell Hardness/Velocity


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bluetopper
March 15, 2008, 11:22 AM
Do any of you know if there is a chart on the net that tells min/max recommended velocities for lead bullets according to it's hardness on the Brinell scale.
I know you get leading going too far either way outside the perimeters of the lead projectile you are shooting and optimum accuracy is lost.

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Wil Terry
March 15, 2008, 05:58 PM
I do not believe there is such a chart because Brinnell has damned little to do with leading one way or the other, contrary to public opinion. On the other hand I've only been doing this for 57 years now so WHAT do I know...???

45crittergitter
March 15, 2008, 06:40 PM
Only info I have:

1422 x BHN = minimum obturation pressure (psi),

or

pressure/1422 = maximum BHN

Walkalong
March 15, 2008, 08:25 PM
5 bhn-7110 yield strength
6 bhn-8532 yield strength
7 bhn-9954 yield strength
8 bhn-11376 yield strength
9 bhn-12798 yield strength
10 bhn-14220 yield strength
11 bhn-15642 yield strength
12 bhn-17064 yield strength
13 bhn-18486 yield strength
14 bhn-19908 yield strength
15 bhn-21330 yield strength
16 bhn-22752 yield strength


Brinnell has damned little to do with leading :what:
Guess you have been just plumb lucky all these years.
It definitely does not work if you have the right hardness, but the wrong diameter, I'll give you that. :)

Wil Terry
March 15, 2008, 08:50 PM
My S&W M39 9MM would lead to a farethewell with hardcast lead bullets of .355", .356", and .357". The barrel itself was .355" on my tri-mike. The leading itself would fill the entire grooves from one end to the other then curl up outta the grooves and be sticking out of the barrel a bit. Worst leading i have ever seen.
That same barrel shot spot free with swaged 9MM or 38 bullets and velocities above 1200fps. That was a long time ago and I decided right then and there the so-called HARD CAST BULLET was a fraud as far as preventing leading was concerned. It was how good the barrel was, how good the lube was, was the bullet soft enough to easily be cut with a fingernail, which propellent was being used, and how big the bullet had to be. Two thousands over groove diamter pleased me just fine usually.
[ PREPARATION is correct...I think...]

Walkalong
March 15, 2008, 09:21 PM
That same barrel shot spot free with swaged 9MM or 38 bullets and velocities above 1200fpsBecause it was the right hardness for the pressure/velocity.

Hard cast bullets are not the cure for all leading. They can cause it as well as prevent it depending on the pressure behind it.

Try a hard cast bullet in the .38 at low pressure/velocities and it will lead the gun all to H***

Try a soft swaged bullet in the .357 at high pressures/velocities and it will lead the gun all to H*** :)

[ PREPARATION is correct...I think...]Yep.

It was how good the barrel was, how good the lube was, was the bullet soft enough to easily be cut with a fingernail, which propellent was being used, and how big the bullet had to be..
All correct, even the "soft enough to", because it needed that hardness of bullet, not a harder bullet, to match the pressure/velocity.

With the hard cast bullets you were getting flame cutting because the bullet was too hard for the pressure/velocity and it was not obturating and filling the bore, thus the flame cutting and spectacular leading for the entire barrel. (entire barrel is a clue here.)

snuffy
March 16, 2008, 12:14 AM
Get and read Richard Lee's loading manual. In it, you will find his ideas behind matching hardness with pressures. But don't ask me, I'm not finished reading it yet.

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