Okay, this one's bound to stir up some controversy. I recall reading (in Handloader, I believe), that Veral Smith had figured out a basic rule of thumb regarding chamber pressure required for cast bullet obturation. If memory serves me correctly, this formula is bullet hardness (in BHN) X 1422 = chamber pressure in CUP required for complete obturation. This must obviously assume correct bullet sizing. This would mean that a bullet with a BHN of 15 would require a chamber pressure of 21,330 to obturate and seal the bore. By the same token a BHN of 22 would require 31,284 CUP to obturate the bullet. This does not seem unreasonable until we look at the lower pressure loads like 38 spl. and 44 spl. none of the standard loads hit anywhere near the 18,486 CUP a 13 BHN bullet would require. 13 BHN is about standard wheelweight territory. I just remelted 250 .38 wadcutters because they hit 15 BHN. Now I wonder if this was necessary. Does Verals formula match your own experiences?
Verals rule of obturation
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Pourboy
veral smith is one of our genuine Gurus. He has brought a ray of enlightenment itto the cast bullet arena and has shattered many myths and old wives tales.
His ideas(actualyKNOWLEGE) are almost like the Holy Word. i admire him . But I do not take any chances on getting something to happen. I size my gas-checked cast bullets at least 0.001 to 0.112 in. over GROOVE size and my bare botommed(no gas-checks) cast bullets to 0.002 t0.003 over the groove size.On top of tha trI also oven heat treat the bullet to a 22-24 bhn. This way nothing is left to chance. I've not leaded a bore in many many years. I am sure Mr,Smith is right but why take the chance? Do the (obturation) first and you know you wont be mineing lead.
tbc
veral smith is one of our genuine Gurus. He has brought a ray of enlightenment itto the cast bullet arena and has shattered many myths and old wives tales.
His ideas(actualyKNOWLEGE) are almost like the Holy Word. i admire him . But I do not take any chances on getting something to happen. I size my gas-checked cast bullets at least 0.001 to 0.112 in. over GROOVE size and my bare botommed(no gas-checks) cast bullets to 0.002 t0.003 over the groove size.On top of tha trI also oven heat treat the bullet to a 22-24 bhn. This way nothing is left to chance. I've not leaded a bore in many many years. I am sure Mr,Smith is right but why take the chance? Do the (obturation) first and you know you wont be mineing lead.
tbc
Gentlemen and others;
My experience with cast bullets has been with the larger calibers, 45 and 44 with some 357, in rifles and pistols. I've not experienced leading, with the exception of the rare use of factory swaged lead bullets, for the past 20 years.
I followed Veral's idea of sizing the bullet to fit the cylinder throats in revolvers, lap the constriction where the barrel and frame meet. I shoot moderate loads some where around 1,000 FPS in S&W 45 Colt, 1,200 in a Colt Anaconda, using 255 gr. plain base WW slugs.
I use the same wheel weight alloy in my 45-70 the 350 grain and 445 grain slugs sized 460 for both rifles works great. Again no leading. The powder charges are not mild, 52 grains behind the 445 gr. and 52 grains behind the 350 gr.
I've tried the heat treating and dropping the hot slugs into cold water, from the mold. I've not found any benefit for my shooting.
Am I missing something here?
Jim
My experience with cast bullets has been with the larger calibers, 45 and 44 with some 357, in rifles and pistols. I've not experienced leading, with the exception of the rare use of factory swaged lead bullets, for the past 20 years.
I followed Veral's idea of sizing the bullet to fit the cylinder throats in revolvers, lap the constriction where the barrel and frame meet. I shoot moderate loads some where around 1,000 FPS in S&W 45 Colt, 1,200 in a Colt Anaconda, using 255 gr. plain base WW slugs.
I use the same wheel weight alloy in my 45-70 the 350 grain and 445 grain slugs sized 460 for both rifles works great. Again no leading. The powder charges are not mild, 52 grains behind the 445 gr. and 52 grains behind the 350 gr.
I've tried the heat treating and dropping the hot slugs into cold water, from the mold. I've not found any benefit for my shooting.
Am I missing something here?
Jim
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6,655 Posts
My experiance agrees with Mr. Smith.
Like ArkyPete I have not had great sucess with quenched or heat treated bullets.
I cast my bullets pretty soft. Generaly between 10 - 12 BHN. I have seen significant obturation in low power pistol and rifle loads. The .32 H&R Mag. and plinker .45-70.
My father and I built a Facklers box. This is a water trough. Fackler used zip lock bags. We used white trash bags. The trough is about 8" wide X 10" deep. You need a safety back stop. When you shoot into the water the bullets are pretty much undesturbed. You get a good idea of whats happening with the bullet base.
Like ArkyPete I have not had great sucess with quenched or heat treated bullets.
I cast my bullets pretty soft. Generaly between 10 - 12 BHN. I have seen significant obturation in low power pistol and rifle loads. The .32 H&R Mag. and plinker .45-70.
My father and I built a Facklers box. This is a water trough. Fackler used zip lock bags. We used white trash bags. The trough is about 8" wide X 10" deep. You need a safety back stop. When you shoot into the water the bullets are pretty much undesturbed. You get a good idea of whats happening with the bullet base.
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3,364 Posts
For a little more on the subject, please see the FAQ pages listed here:
<a href="www.beartoothbullets.com/faq/index.htm" target='_blank'>www.beartoothbullets.com/faq/index.htm</a>
Hope you find the infor helpful!
God Bless,
Marshall
<a href="www.beartoothbullets.com/faq/index.htm" target='_blank'>www.beartoothbullets.com/faq/index.htm</a>
Hope you find the infor helpful!
God Bless,
Marshall
I too, avoid heat treating and quenching. I've found no practical advantage to it for what I shoot. I even air cool my bullets, how old-fashioned! However, my "normal" alloy does run 15 BHN. Perhaps a bit hard for everyday useage. But easily adjusted.
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