I have a new article on Brinell hardness....

[Harry O]

and what it means to the bullet caster.

http://www.sixshootercommunity.com/h...etcasters.html

[bigdog454]

Great article!

[felix]

Excellent, Harry! ... felix

[theperfessor]

Very good article well worth reading. Thanks for posting link.

[Charlie Two Tracks]

Got it saved to the computer.

[Marlin Junky]

Well heck, since I'm applying an annealed gas check to most of my boolits, I'm going right up to the BHN*1422 value determined from my 100% reliable QuickLoad! If that doesn't work then I'm practically guaranteed a non-annealed gas check will solve all my problems.

But seriously, thank you for posting that interesting article. I have been wondering how the 1422 was derived... and I've been using 1440 all this time. Now I finally know what's been ailing my '06!

In all reality though, isn't the pressure data published by Lyman more reliable than that generated by QuickLoad? I can't cite exact discrepancies off the top of my head, but I sure seem to recall some disagreement between Lyman and QuickLoad.

MJ

[Marlin Junky]

I've got another issue with respect to this hardness thing in rifles: How does one know if their boolits are too hard? Is it by looking at the fouling near the muzzle, perhaps caused by too much friction? Let's assume we're shooting boolits .002" over groove and obturation or lack thereof doesn't apply.

MJ

[Harry O]

I use the 1,422 number for plain base bullets. I have not done any extensive tests on gas checks, but it seems that going about (and I stress the ABOUT) 1-1/2 times that number (or roughly 2,100) is pretty close to the upper limit for gas checks.

Rough number, I use plain base up to about 22,000psi. Above that, it is not worth making it hard enough for plain base. I use gas checks with up to about 32,000psi. Above that, I use jacketed.

I do not have one mix. I match the hardness of the mix to match the pressure. That means that a 5gr load of Trail Boss in a 38-40 CAS load is just about as soft as I can make it. A .38 Special +P load will be about Bhn 15-16. With gas check, I start soft lead again, but by the time I get to the top, I am back up to about Bhn 15-16.

I figure the hardness of the mix before doing any casting, by using formulas in a different article. It is:

http://www.sixshootercommunity.com/h...ingcircle.html

I wish I had better ways to get the pressure of a load. I do not have a computer program. A friend of mine had one that we played around with once and it came up with some strange results. For example I got a number of cheap Winchester White-Box 9mm factory loads that were loaded out to maximum OAL. They were just a little too long for my Browning P-35. I put them in a loading press and shortened them to what the OAL length was given for handloading. From memory, it was about 1/32" shorter. The computer program showed that shortening it upped the pressure to proof load levels. They shot great, though.

I do have a Powley Computer that I have great faith in. I used it before there were cheap chronographs available. After I got my first chrono, I was very pleased to find that the Powley was VERY accurate, at least when it came to velocity. It also figures pressure and because of the velocity results, I trust it. Of course, that is only for rifle loads with IMR powders.

I have a few loadbooks that list pressure and I go by those, with nothing else to go on. So far, so good.

[Bret4207]

Okay, maybe I'm dense, but this sentence is bothering me, "Remember that as long as the load applied is in the elastic range, the bullet will return to its original size and shape after the load is removed (ie, as the bullet leaves the barrel)." Are you saying that any common lead alloy in use for cast boolit shooting will travel down the barrel and return to it's form from beofe it traveled the barrel? I have never see anything like this. Anytime any change is made to any of my lead alloys it always results in the change remaining. This sounds like you're describing spring steel. So, I'm confused.

Also, we can have three different alloys giving the same Bhn reading that react in 3 different manners to a given load or 1 alloy treated 3 different ways that shows 3 different Bhn readings and reactions. I think the makeup and treatment of the alloy has just as much to do with our accuracy and success as sheer Bhn readings.

[Marlin Junky]

Okay, maybe I'm dense, but this sentence is bothering me, "Remember that as long as the load applied is in the elastic range, the bullet will return to its original size and shape after the load is removed (ie, as the bullet leaves the barrel)." Are you saying that any common lead alloy in use for cast boolit shooting will travel down the barrel and return to it's form from beofe it traveled the barrel? I have never see anything like this. Anytime any change is made to any of my lead alloys it always results in the change remaining. This sounds like you're describing spring steel. So, I'm confused.

The difference in dimensions between the boolit alloy under load and not under load, while still in the elastic range, would probably be imperceptible to the handloaders' caliper.

Also, we can have three different alloys giving the same Bhn reading that react in 3 different manners to a given load or 1 alloy treated 3 different ways that shows 3 different Bhn readings and reactions. I think the makeup and treatment of the alloy has just as much to do with our accuracy and success as sheer Bhn readings.

You're going to need to explain that one with some examples; however, your suspicion, "I think the makeup and treatment of the alloy has just as much to do with our accuracy and success as sheer Bhn readings", may be correct for other reasons; e.g., coefficient of friction or malleability, perhaps.

MJ

[Echo]

Great article, Harry O. Printed & saved in my Big Book.

Bret, remember we are talking about the base of the boolit. Sure, the rifling is impressed on the sides, but the pressure there HAS to be greater than the pressure on the base (because it HAS changed and didn't go back to the way it was).

[Marlin Junky]

Bret, remember we are talking about the base of the boolit. Sure, the rifling is impressed on the sides, but the pressure there HAS to be greater than the pressure on the base (because it HAS changed and didn't go back to the way it was).

The forces on a base are compressive, those that form the rifling are shear... two different animals.

MJ

[Bret4207]

You're going to need to explain that one with some examples; however, your suspicion, "I think the makeup and treatment of the alloy has just as much to do with our accuracy and success as sheer Bhn readings", may be correct for other reasons; e.g., coefficient of friction or malleability, perhaps.

MJ

Okay- We can take 3 different lead alloy samples- say aged straight WW, 10-1, and fresh, juiced WW with more Sn/Sb. All 3 can be around 11-12 Bhn. All 3 will react differently to sizing, launch and impact with the same powder load. We can also take 1 alloy, say juiced WW, treat it 3 different ways and get 3 different Bhn readings. It will react differently as above.

IOW- Bhn alone isn't the whole story. Bhn alone = HARDCAST is mo' bedder!!!, which as we all should know by now isn't true. I find the concentration on Bhn used solely as the determining factor in what a given alloy will do with a given pressure to be inaccurate based on my experience.

[Harry O]

Marlin Junky has answered the questions as well (or better) than I could. As far as the different makeup for three mixes that have the same Brinell, that may be somewhat true during casting. However, for normal types of lead/tin/antimony mixes used by handloaders, I have not found any significant difference in how it acts in the barrel.

However, the difference in makeup makes a major difference in how well it casts. For example, a Bhn 11-12 mix (from your example) with strictly pure lead plus antimony will be difficult to cast if the bullet is very complicated at all (such as a hollow-base bullet). Pure lead plus enough tin to bring it up to Bhn 11-12 would cast like a dream. However, from my experience there is no major difference with how well the two handle an equal amount of pressure in the same gun.

I have also have taken ONE mix and cast it and quenched it in different ways. When air-dropped, a 100gr bullet had the highest Bhn. The 200gr bullet was approx 3/4 to 1 Bhn softer. A 350gr bullet was approx 1 Bhn even softer. Even though the mix was EXACTLY the same, the difference was because how quickly the the bullets cooled -- the heavier the bullet, the longer it took to cool. The same test mix and bullets dropped into cold water directly from the mould gave Bhn's that were pretty close to equal and approx 50% more than the air-dropped ones.

They all behaved during shooting exactly how I would have expected by the Bhn each had even though the mix was exactly the same.

[Bret4207]

Your experience doesn't match up with mine. I have seen the make up of the alloy effect both accuracy and reaction to the pressure with similar Bhn, but different makeup. I don't have the technical training to put my observations into words beyond saying IME it does happen.

[Bass Ackward]

I wish I had better ways to get the pressure of a load. I do not have a computer program.

Great article on the metal part Harry.

The main message is that is simpler / easier if you stay elastic. Especially if you use just a surface lube. Surface lubes work when the bullet design can support itself. But it ain't just pressure Harry. More factors enter the equation that I can't explain.

I just know that if I work under the right conditions, the strongest part of my bullet should be the lube. Supported by hydraulic forces and steel, I can establish "mold like" conditions to control the plastic state. (The real question is, if I control movement, is the plastic state ever reached?)

If I can pull this off, and if the gun can maintain those conditions (seals and doesn't build fouling) I can operate in the plastic zone. Especially if I have a GC where the force is the highest requiring the most lube and I balance antimony and tin. I think that this is why you can actually shoot better at times when you do foul because the lead can then be smoothed by the next slug and seal where the clean barrel could / did not.

If I can't establish and maintain this during the plastic period, or if the bullet design won't allow me, (must have grease grooves that are deeper than the rifling to allow 360 equalization of hydraulic force) then I need a harder bullet or to cut pressure to get back to non-deformity. That is why choking is favored by many. The lube is the first thing to go without seal and it leaves from the area where it is needed most. (the base)

I find that it's when you enter the plastic state that your mix becomes important. And this is where I become the most ignorant. The higher the antimony that you have free (more than tin content) the more problems that are encountered. And it seems that you are better with lower amounts period.

That seems to be why the old lead tin mixes were preferred when they knew they were going plastic and why guys seem to do well with 50/50 WW and pure. It could be as simple as going back to fouling that does not build and seals. But again, no rules.

[357shooter]

Sorry to be a lone voice of disagreement, however:

My test results are very different. I only load for 357/38 revolvers with the primary objective of accuracy. After testing a few thousand boolits the most accurate alloy is pure lead with a 10inch strip of solder for every 10 lbs, with a 5.1 load of 700X. That's roughly 30,000PSI with the 168 grain Keith boolit and roughly BHN 7 (or so). Very close to that is 4.9 grains of HP-38 which is 27-28,000PSI.

Each time alloy BHN was increased the groups opened up, each time I lightened the load (less pressure) the groups opened, each time I used a different powder the groups opened.

If the boolit design doesn't work in the gun (nose to throat in my case) maybe these calculations can be helpful. However my test results say they flat don't work. At least in my 357 revolver, matching the alloy to the pressure doesn't help accuracy at all.

Rifles, that's a whole nother discussion that I can't comment on as I have no idea. Matching pressure to the alloy may matter.

[Harry O]

I wish everyone who posts to this website would get the book by Veral Smith, Jacketed Performance with Cast Bullets (from memory). Where the Lyman books are a great start, the Smith book is an advanced degree in casting.

Naturally, one of the reasons I like it because Veral Smith believes in the 1422 number (as does Richard Lee and several others). Veral Smith also can go over that number at will. He is one of the very few people who has the experience and knowledge to do so. For beginners, or for people who don't want to waste their time trying to find the magic combination of factors to exceed the 1422 limit, this is the quick and easy way to get accuracy. As Bass Ackward said, "The main message is that is simpler / easier if you stay elastic." That is EXACTLY what I am saying.

As far as those who do not have the same experience as I did, so be it. I am not going to call you names. I have done specific experiments, varying one item at a time to find out what they individually do. These experiments agree with my engineering training. Going over the yield point never does good things to a bullet.

Just a couple of comments. Mr Smiths book has a GREAT picture of an experiment he did. He made a mould for a bullet that was bore diameter. At both ends, he created a belt that was a little over groove diameter, to seal it. Then he cast a bunch up with pure lead and shot them with increasing amounts of powder. The rear deformed. The higher the load, the more deformed it was, working from the rear towards the front. The bullets were put side by side and photographed. You could easily see the progression with increasing pressure. Of course, the bullet was not accurate. It was done to prove that deformation starts at the rear of the bullet and works forward if the bullet is not hard enough. It was pretty eye opening to me.

Another thing is about the "old guys" who used 10:1 lead/tin mixes at higher pressures than this formula indicated. That is true, but if you go back and carefully read Keiths book, Sixguns, he says several places that there was some leading with that combination. As long as he could get decent accuracy, scrubbing the leading out was a necessary evil. I would say that Keith was another who could exceed the 1,422 limit, but I am not sure that it was at will. From those books, it was obvious that he was always experimenting to find a combination that would work for him. When he found it, he stayed with it.

Bass Ackward: I have experimented with VERY hard cast bullets (up to Bhn 37-39). The first experiment was with straight monotype, dropped from the mould into cold water. The mix was approx 17.5% antimony, 9.5% tin and the rest lead. The bullet was so brittle that crimping the case into the crimping groove cracked the bullet. There was entirely too much free (unalloyed) antimony in the mix. The lead could only take about 6% of the antimony in alloy and the rest (approx 12% more) was between the lead crystals.

I increased the amount of tin to match the amount of antimony. The end mix was approx 15% antimony, 15% tin, and the rest lead. The excess antimony alloyed with the tin and the end result was a tough bullet that would take a full pressure load (approx 45,000psi and nearly 2,200fps). With a Bhn 15-16 mix (in the same bullet and same gun), the accuracy went bad at about 1,400fps and visible leading started about 200fps higher. I believe I put in a little more tin than was absolutely necessary to soak up the rest of the antimony, but I was in a hurry. I may go back and refine the mix later.

I have not done as much experimenting with lube. From the limited experience I have, I think it is hard to increase the maximum limit by very much by only changing lube. However, a bad lube will reduce the limit by quite a bit. Several lubes that I made were bad lubes. I have settled on commercial NRA 50-50 lube for higher pressure loads. It seems to work for me.

[32ideal]

HARRY O have you performed any tests using plastic wads (PVC, LDPE, HDPE, Plastic milk cartons ETC) on the base with plain base bullets?
32ideal

[Harry O]

31 Ideal: No I have not. I use commercially available fiber wads between the powder and the bullet with BP loads. It does seem to help them a bit. I have not tried them with smokeless loads because the smokeless powder does not completely fill the case to the bottom of the bullet and hold the wad in place. I would not want it to fall down and then get propelled against the bottom of the bullet when the powder ignites. Who knows what would happen.