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Lead Bullet info: 45/70


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I'm looking to load up some 'moderate' velocity LEAD bullets in my 45/70 and

need to know appropriate 'hardness' of the lead being pushed around 1000 - 1300 fps.

 

Seems like one bullet maker brags about their bullets for 45/70 being Brinell 15.

 

Another maker brags about their bullets being 18.

 

Is one more appropriate than the other for the velocity ranges mentioned?

 

Thanks.

 

..........Widder

 

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I have used Lyman #2 equivalent for .45-70 bullets running around 1430 ft/sec with smokeless powders in an original HiWall.  Don't recall the exact hardness, but somewhere around BHN 15-18.  With open iron sights and when my eyeballs were younger, I could get 10 rounds into 2 inches at 100 yds

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Posted (edited)

I have tried Bear Creek Supply moly coated 405 grain 45-70 bullet at around 1300 fps and it worked great with no leading.

Brinell hardness is around 12, if I remember correctly.

 

Bear Creek Supply

(209) 874-4322

 

https://www.bearcreeksupplybullets.com/

 

Edited by Pat Riot, SASS #13748
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Posted (edited)

For that velocity range(1000 to 1300 fps), bullet hardness is real flexible.  But you will probably get the most accurate results with Brinnell Hardness of 12 at those speeds. 

 

Harder alloy than that can produce gas cutting on the lower part of bullet, giving you some leading problems and less accuracy.

 

I've gotten 1" groups at 100 yards with a 300 grain cast bullet, 12 Brinnell, conventional lube, sized 0.459", and 19 or 20 grains of 2400, from an open sighted Marlin 1895 with Ballard cut rifling.  Runs about 1250 FPS.  Makes a very nice load for out to 200 yards, and very soft shooting.

 

good luck, GJ

 

 

 

Edited by Garrison Joe, SASS #60708
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If you are keeping it under 1300 fps you can run them as soft as you want, if you are shooting an original trapdoor the best velocity will be about 1150-1160. If you are shooting something like an H&R Buffalo Classic you can jack it up a bit. We are going to be at TN state I can bring some loaded 300g rounds that I have found to accurate out to 300 yds.

kR

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1 hour ago, irish ike, SASS #43615 said:

It my terms of hardness, lead at 20/1 lead to tin.

Brinell hardness of 10


nifty chart…;)

http://www.pnjresources.com/Hardness of Lead Alloys.htm

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There are several mistakes and inaccurate data for hardness in that chart from PNJ Resources.  For example, the 1:1 mix of soft lead and linotype alloy's composition does not add up even close to 100% as it should.

 

I find the Cast Bullet Alloy Hardness calculator at Cast Bullet Association to be more accurate and it's able to calculate any reasonable alloy's hardness.

Alloy Calculator - Cast Bullet Association

 
good luck, GJ
 

 

 

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Widder,

I looked at 27 loads within the 1,000~1,300 fps range.
PSI ranges from 11,100 to 25,600.
BHN associated with these PSI range from 8.7 to 20.

AA5744 / Shooters World Buffalo Rifle is in the middle of your FPS range.
BHN ranges from 9.1 to 14.8





 

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Widder,

 

Jackson Longstreet is an expert on the .45-70.  He hasn't shot regular cowboy with us at Cleveland, TN in several years, but he shot long distance with Too Tall until recently.  He still sets out the steel for us at the regular Cleveland matches and he is a member of the national SASS forum.  PM him for info.  He likes Missouri Bullet Company bullets (I can give you the Cleveland discount code).

 

He has super info on bullets, loads, and loading techniques.  If have trouble getting in touch with him, let me know.  I talk to him on a regular basis and I am currently doing some Civil War leather work for him.

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There is a relationship between chamber pressure and lead hardness.


The effective PSI / 1279.8 will give you the optimum BHN.


Too soft, the base lead will melt and cause barrel leading.
Too hard, the base fails to obturate (seal) and you get blow-by from the cartridge gas.


It's a Goldilocks thing.

 

 

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Posted (edited)
Quote

Too soft, the base lead will melt and cause barrel leading.
Too hard, the base fails to obturate (seal) and you get blow-by from the cartridge gas.

 

 

Ummm, kinda backwards with the actual causes/results.

 

Too soft, and it's harder (not impossible) to lube well enough to prevent leading from friction with the barrel.   But, .22 ammunition is soft lead bullet at 5-6 BNH and 1000 to 1300 FPS. Years of research has developed lubrication for those lower speed loads that don't lead.   At the higher end of those ,22 velocities, copper plating is used in most ammo to prevent leading.  And why .22 magnum rimfire bullets are thinly jacketed.  

 

This is also what caused .357 magnum ammunition in the 30s and 40s to get the reputation of being a "heavy leading load" when first manufactured by the factories with soft lead .38 special bullets.    Because muzzle velocity increased to 1800 FPS with the same soft bullets that .38 Special shot just fine at 1000 FPS.

 

Too hard a bullet, and bullet will not obdurate to fit the grooves (if the bullet is under size) and gas cutting of the lower section of the bullet deposits lead fragments/droplets onto the barrel wall.    From studies of fired bullets, the lead comes from the shank of the bullet, not a melted base.

 

good luck, GJ

Edited by Garrison Joe, SASS #60708
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Posted (edited)

Velocity increased.. because the PSI went up.
Pressure is what makes the bullet obturate in the rifling.
There is indeed a relationship between PSI and BHN.

If the shank is the cause of leading, and not the base, thanks for the update.

BTW, it is "obturate" if meant as the lead bullet expanding to fit the grooves.
"Obdurate" is refusing to change one's opinion or course of action.


 

Edited by bgavin
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Missouri Bullet casts 2 bhns of 12 and 18. All their cowboy bullets are 12. They have a formula on their site for calculating what hardness for a given velocity.

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I'd posit that the lube used is equally important in the equation as the hardness of the lead.  Proper sizing is, as I'm sure you know also a major factor.  I like the 500 grain loading, really makes for a big push when you pull the trigger.

 

BP usage will help to keep your barrel adequately fouled to reduce leading.

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Are you shooting the Holy Black or the heathen smokeless? Kind of a different ball game. If I ever get to be World Dictator it will absolutely be forbidden the load smokeless in a .45/70.

JHC :P

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