Question on cast bullet bhn

4.5K Views
Last Post 25 June 2014

Standard Member

flinter posted this 23 June 2014

I like to ask why some bullets with a BHN of 10 or 12 I can scratch a line in them with my finger nail others with the same BHN is a little harder takes more then a finger nail to scratch them I just got in a batch of 38-55 from RimRock bullet company 240 FN casted at a BHN 15 I loaded a few with IMR 3031 they shot excellent not as good a my sarco mould # 738 in 255 grains BHN 10 and 12 (yep these are soft lead ) no gas checks with 34.5 IMR 3031 and no barrel leading FPS high 1700 The Rimrock bullets looked real hard but yesterday a good friend has a lead harness tester and the Rimrock boolet came in at 12 from the readings on the lead tester. I wonder if they add a different mix to make the surface of the bullet a little harder

Attached Files

12 Comments

Order By: Standard | Newest | Votes

Standard Member

onondaga posted this 23 June 2014

http://www.castbulletassoc.org/view_user.php?id=8170>flinter A simple answer is that lube differences effect finger nail scratch testing and alloys containing Antimony can have hardness dramatically effected by how the bullets were cooled after casting.

Also note that barrel leading is not related to velocity within reason at all with cast bullets when the alloy strength matches the load level and the bullets fit the firearm.

Leading is caused by undersized bullets wobbling down the bore and gas jetting and bullets that are too soft or too hard for the load level being shaved by rifling. A rough bore will also worsen leading. More critical factors also come into play the harder a cast bullet alloy is. Fit of hard bullets is more critical and harder/brittle alloys are shaved more readily by rifling than bullets of an alloy that matches the load level.

The ductility and strength of Lyman #2 alloy is the reason it has been the #1 choice of cast bullet shooters for very well over 100 years. I use it for everything for hunting other than Muzzle loading projectiles that I cast with .999 pure lead. I practice center-fire cast shooting with a BHN 15 alloy I mix from Lino/Pure at 1:1, that is the same hardness as Lyman #2 and hits to the same point of aim but doesn't expand as well or dependably on impact with game animals as Lyman #2. My homebrew practice alloy is very similar to commercial Pistol “Hardball” BHN 15 alloy.

Gary

Attached Files

CBA Member

99 Strajght posted this 23 June 2014

I have mixed two batches of lead-tin-antimony with the same BHN but with different % and have had two totally different bullets. One is 92-2-6 and the other is 88-6-6. Both will brinell about 15 but shoot to different points of impact and different expansion. The 92-2-6 will not expand. The 88-6-6 will expand better and is more accurate. The group size of the 88-6-6 will be about 1/2 the size of the other.

Attached Files

Standard Member

flinter posted this 23 June 2014

I think Rimrock uses 2/6/92 alloy I wonder will they be any good for deer hunting at FPS 1700 or are they to hard to use. I have other cast sarco mould # 738 255 FP BHN of 10 Is my hunting boolet

Attached Files

CBA Member

99 Strajght posted this 23 June 2014

I do not think you will have any trouble killing with a 38 cal. 240 gr. bullet no matter how hard. With a bullet that size you do not need expansion. I have killed deer with 100 gr. 13 brinell from a 250-300 and a 257 Rob. with no problem.

Attached Files

CBA Member

joeb33050 posted this 24 June 2014

flinter wrote: I like to ask why some bullets with a BHN of 10 or 12 I can scratch a line in them with my finger nail others with the same BHN is a little harder takes more then a finger nail to scratch themThe simple answer is that the hardness is not the same. I just got in a batch of 38-55 from RimRock bullet company 240 FN casted at a BHN 15 I loaded a few with IMR 3031 they shot excellent not as good a my sarco mould # 738 in 255 grains BHN 10 and 12 (yep these are soft lead ) no gas checks with 34.5 IMR 3031 and no barrel leading FPS high 1700 The Rimrock bullets looked real hard but yesterday a good friend has a lead harness tester and the Rimrock boolet came in at 12 from the readings on the lead tester. I wonder if they add a different mix to make the surface of the bullet a little harderAvailable lead hardness testers, LBT, LEE, etc. are notably poor and unreliable in estimating hardness. Teenyl sample sizes and varied procedures make them stupifyingly inaccurate. See the test we performed, and the test of hardness testers on the LASC site.

Attached Files

CBA Member

99 Strajght posted this 24 June 2014

I have had very good results with the Lee lead tester. It does take a little practice in getting used to using and reading the scale but it works spot on. And I can repeat the reading time after time.

Attached Files

CBA Member

joeb33050 posted this 24 June 2014

Spot on?

Attached Files

3.3 CAST BULLET HARDNESS REQUIREMENTS.doc

CBA Member

99 Strajght posted this 24 June 2014

After reading the thesis on Cast Bullet Hardness Requirements I have more questions then when I started. The test on bullet hardness was flawed. There was no listing of the tools used to take the measurements except for Bill McGraw who used a LBT. Were these people trained to take measurements. What was the time factor. Cast bullets harden over time. I stand by my statement that I can read bullet hardness with a Lee tester. After that the rest of the article went on to prove just what I was saying. Different mixtures shoot different. Maybe someone should do a test on bullet hardness testers.

Attached Files

CBA Member

joeb33050 posted this 24 June 2014

99 Strajght wrote: After reading the thesis on Cast Bullet Hardness Requirements I have more questions then when I started. The test on bullet hardness was flawed. There was no listing of the tools used to take the measurements except for Bill McGraw who used a LBT. First page, “Here is a table...explains what was tested, by who, with what testers. Also explains the hideous TIME FACTOR. Carefull reading, maybe a couple of times, makes for understanding and clarity.Were these people trained to take measurements. What was the time factor. Cast bullets harden over time. I stand by my statement that I can read bullet hardness with a Lee tester. After that the rest of the article went on to prove just what I was saying. Different mixtures shoot different. Maybe someone should do a test on bullet hardness testers.

Attached Files

CBA Member

joeb33050 posted this 24 June 2014

99 Strajght wrote: After reading the thesis on Cast Bullet Hardness Requirements I have more questions then when I started. The test on bullet hardness was flawed. There was no listing of the tools used to take the measurements except for Bill McGraw who used a LBT. Were these people trained to take measurements. What was the time factor. Cast bullets harden over time. I stand by my statement that I can read bullet hardness with a Lee tester. After that the rest of the article went on to prove just what I was saying. Different mixtures shoot different. Maybe someone should do a test on bullet hardness testers. Try reading this, it explains the “other” hardness tester test.http://www.lasc.us/Shay-BHN-Tester-Experiment.htm