lead bullet hardness....

[davecutts]

I spoke to a local guy last night who has started casting bullets (because who wants to pay shipping on lead) on interesting thing of note he said was that lead needs to cure or age for thirty days to obtain real hardness and therefor less leading.  I think he said the bullets out of the mold (after cooling I hope) were a 6 or 7 and after aging for a month they curred up to 9.  I'm not sure what those numbers mean, however he says that week old bullets in his steel gun leaded badly, and a month later no lead.

Is there truth to this accertion?

Why and how?

[Flexmoney]

I don't know much about the hardness numbers...but, someone was recently telling me numbers in the low 20's range for 45 LSWC.  

???

[davecutts]

Okay numbers shnumbers... what about the ageing of the lead?

[Patrick Sweeney]

I vaguely remember somehting on that.  I'll have to look it up.  When listing numbers, you have to know what scale is being used.  "5 or 6, going up to 9" on what?  The old Saeco hardness tester?  Rockwell C?  Rockwell B?

[Carlos]

I wish I could add hard facts to the speculation, but no such luck (or facts) so I'll add recalling an article on "hardening" cast bullets by heat treating - something like bake cast, sized bullets on a cookie sheet in ordinary oven to significantly less than 700 degrees (like 250-300 deg) for X hr. and let cool to harden them up x number on the scale; then lube, load, fire. Presto, little to no leading.

As to ageing; perhaps its the surface oxidation coating that  needs to form over 1 month.

Where are the casting gurus now that we need you?

[spook]

I think with lead you use the Brinell scale and have a hardness of 15-20 for minimal leading. Sometimes you get a number before the Brinell number and I don't know what that is, but it's usually around 7-9. I have never seen anyone use the rockwell scale on lead, but I might be wrong.

[cukrus]

From Cast Bullets an NRA publication written by Col. E.H.Harrison,  I quote "Lead alloys do harden considerably for a time after casting ." (Pure lead won't.) Most of the hardening occurs within 10 days.  I have found changes from 12 Brinell hardness to 16 BH on my wheel weight alloys.  Heat treating can raise the hardness considerably. Specifics can be found in the same publication or a web search of the subject.  The trick is rapid quenching after 50-60 min of heating the bullets of an appropriate alloy to just below melting (slumping) point;  these will work soften.

[Carlos]

Thanks Kukrus - for supplying appropriate authority. D.

[SherlockWV]

I don't know anything about hardness and aging but I started a thread to see if there was a consistent weight varible for lead bullets. This was after I weighed 6 different bullets (9mm) from 6 different boxes that were supposed to be 148 gr. I discovered that there was a high of 150.3 and a low of 146.7. Fortunatly someone who used to work for a major lead bullet manufacture took note and informed me that the ratio of antimony, alloy & lead have more to do with harness than any "cure time". I am sure that it all adds into the equation but one thing that he shared was that the harder the bullet the faster you have to push it to avoid "leading". The oppisite is true for softer bullets. His professional experience showed that a hard bullet pushed too slow will lead up the bbl. I am quoting now as he said that " in order to avoid leading with hard bullets you have to load to where they are "screeming" out the bbl. Since I read his advice, I have been running the bullets between 17 and 20 over minimum PF. No problems with lead fouling since I changed, plud accuracy and consistency are better. I also tumble my loaded bullets to the point where I actually get a 147 gr. bullet. Wise or unwise it has been working for me. I don't have problems with the bullets but I have a problem hitting the targets. Newbie!! I think that guy used the Brinell Scale. He also said to stay away from wheel weight bullets because of the alloy isn't consistent. But many people do use wheel weights and do so successfully. I guess if the shoe fits wear it.

Safe shooting to all!

[Ray S.]

I've had decent luck with leading using the old "obturation" theory or whatever. 480 times the Brinell hardness equals the pressure required to obturate the bullet base.

[SherlockWV]

Ray - I have never heard to the "obturation theory". Makes sense. Will add this into my log.

Thanks - JC

[TBF]

but one thing that he shared was that the harder the bullet the faster you have to push it to avoid "leading". The oppisite is true for softer bullets. His professional experience showed that a hard bullet pushed too slow will lead up the bbl. I am quoting now as he said that " in order to avoid leading with hard bullets you have to load to where they are "screeming" out the bbl.

You will draw a lot of blank stares with comments like that.

Believe me I know, my experience has been similar, soft bullets for mild loads, hard bullets for heavy loads, and most 45 bullets are just too freakin hard for any sane loading in 45acp.

If you see lead just outside the chamber in lumps and bumps, bullet is too hard, or load too soft.

If you see streaks down the barrel, bullet is too soft , or load is too hot for the bullet.

"Leading" is often discussed without reference to it's origin.

I have heard that Laser cast may behave differently, they have silver in the alloy, and that may affect their " stickiness ", much as stainless steel is " stickier " than carbon steel.

Like I said, blank stares...

Travis F.

[dajarrel]

A few things I have learned about casting my own lead bullets:

Don't bother quenching them by dropping them in water from the mold. Unless you are using tumble lube bullets (from a Lee mold) you will have to size and lubricate the bullet. When you run it through the sizer, the working of the lead as it is swaged to size will cause it to soften up again. Then you will have to wait for it to age harden.

As was mentioned in a previous post, alloy is much more important. If you cast a pure linotype bullet, it is hard to the point of brittleness. The alloy is made up of tin, antimony, and lead. The tin provides mold-ability. It's what makes the lead fill in the mould giving nice clean edges. Antimony in the mix causes the alloy to harden. And of course, lead makes up the balance. I won't get into percentages, but suffice it to say that the higher the antimony content, the harder the bullet.

Size your bullets to .001" over bore diameter. There are several reasons for leading but the one that caused me the most grief was gas blowing by the bullet causing it to melt and deposit lead in the grooves. By sizing at least .001" over, the base of the bullet is more easily pressed into the grooves of the barrel (obturation), sealing them and preventing gas blowby and leading.

If you can regulate the amount of lubricant you put on the grooves of your bullet, experiment with reducing the amount of lubrication used. In my experience, (I load .38,.357, .40, and .45 bullets I cast) I don't push the bullets much over 1000 fps. 99% of the time, I run about 925-950fps in my .40. I have shot at close-up IPSC targets (1-3 yards) and noticed un-burned lube deposited on the target. I only fill one groove of any multi-grooved bullet.

These are just my humble observations which can be documented by most any good book on casting lead bullets. (except the comment on reducing the amount of lube, that has been my on-going experiment )

dj

[TBF]

It seems to me also that the amount of lube on most bullets is excessive, the bullets recovered from pins show hardly any of the lube has been removed, even with loads in the upper range . Mostly 45acp stuff I have looked at .

Travis F.

[SherlockWV]

Travis - Thanks for the confirmation regarding Hard Bullets needing hot loads and visa versa. As mentioned in my post, that info came from someone who used to actually work for a major lead bullet manufacture. This all stemed from me trying to find out if there was an industry standard for acceptable weight differentials. Aparanlty there is not a standard but a comment was made where quality lead bullets generally had a tolerance of 1/2 grain. I was getting a +- factor of 3grs from a local guy who makes bullets. He was quering me in regard to mass marketing his bullet line and aside from his production capabilities I wanted to know if he could produce a bullet within the 1/2 gr. tolerance. Otherwise I believe that he he would have shot himself in the foot. (no pun intended) because word travels fast about the quality of a product.

Talk about a blank stare. I know a guy who has only shot for 2 seasons but with that considered is a pretty darn good shot. He switched to shooting a Para with Hi Caps and was trying to get his loads PF down to minimum. Now he buys his bullets from the same guy as I do and I told him that he was shooting pretty hard bullets so he had to push them faster to minimize leading. Total blank stare. Maybe that is ok for him and others but I want to maximize efficiency by running the proper load for the bullet. Another point the Lead Mfg. guy made was that too hot of a load with a soft bullet causes gases go excape around the bullet.

Now my bullet guy tells me that his weight varible is due to a certain flux problem and that he can fix it by changing the flux. But that is way over my head. Regarding lube, this guy uses so much that I have to clean out my seating die every 200 rounds pr the bullet gets stuck in the die. That is another reason I tumble the finished loads. I admit that I am somewhat radical when it comes to technical stuff but that is just the way I am. I feel more comfortable or free when I know that I have done my technical homework. I know guys who could care less about hardness/softness and powder charges. They just load up, point the gun down range and shoot. And...they shoot well. Perhaps I will get there someday but the truth be known, I kinda get off on the techinical stuff. I like to take things as far into the state of the art as finacially reasonable.

Contiued Safe Shooting - Jc