Hardness Testing Questions

[JudgeBAC]

I just received my awaited Cabin Tree Hardness Tester. After setting it up according to the instructions I have tested a number of bullets and the results seem to be inconsistant? For example, several bullets cast at the same time from the same alloy vary in BHN hardness as much as +- 5. For one bullet I would read a hardness of 15 and for another cast at the same time 20. Am I doing something wrong or is this normal given that I am using non certified alloys? Does it matter if you test with a gas check in place or should I be testing a bare based bullet? Any help will be greatly appreciated.

[MT Gianni]

Yes, you should test a bare based bullet. I would also test an ingot and see if it is the same as my bullets. It is not uncommon for bullets to weigh different depending on the level of the pot when poured. This also may have to do with temperature differences during the pour. Your alloys should test the same as your bullets or there may need to be corrections done in your casting procedure. gianni.

[MGySgt]

Judge - When testing a bullet do not get too close to the edge of the nose, the lead will dent easier on the edge then towards the center.

I have painted the screw head white to make it easier to mark and only do one complete revolution when testing. It doesn't take too much to go too far or not far enough to get a consistant reading.

All bullets from the same castng session should be real close to the same hardness. And as Gianni stated above the bullets and the ingots should test the same.

Drew

[monadnock#5]

I'm not sure how the Cabin Tree works, I have a Saeco. With a Saeco you get one hit per boolit, on either the base or the nose. But from my hardness testing at work, I can tell you that if you take multiple readings from the same source, your indenter has to be at least 2 full diameters away from any previous test. Too close will give you a false high reading. To get good readings, you have to be as absolutely consistent as you can possibly be with each and every test you take.

Ken

[JudgeBAC]

Thanks for the info. I re-read the instructions and learned ( I missed it the first time in my angst to get started) that you must have at least 1/4" of material to test. The instructions suggest filing the bullet nose flat to accomplish this. I am now obtaining more consistent results. While on this subject, sort of, what kind of alloy composition will produce bullets in the 8-10 BHN range of hardness?

[RayinNH]

Judge, this site will answer your alloy question, it's a good one to bookmark...Ray

http://www.lasc.us/CastBulletNotes.htm