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Enhancing Reclaimed Shot ?

Posted: Tue Sep 26, 2017 8:38 am
by mtngun
From my 3150 fps alloy shootout:
First, I added one tablespoon of sulfur to 10 pounds of barely melted J.R. brand reclaimed shot.

Second, I added 0.8 pounds of Rotometals 30% antimony. Guessing that the reclaimed shot started out at 4% Sb, then the enhanced version would end up at 5.9% antimony. The bullets were oven treated at 470F and quenched in water. After aging approximately 2 weeks, the hardness today was 40.5 BHN (4mm, 60#) or 45.2 BHN (10mm, 150 kg), for a 6 - 8 increase in BHN compared to straight J.R. shot.

45 BHN would be great, but when I tried to duplicate that recipe recently, it did not increase hardness one iota over regular J.R. shot. :x

So I am trying again, doubling up on the Superhard enrichment. I took 9.88 pounds of the "bad" batch of "enhanced" reclaimed shot (ERS for short) and added 0.94 pounds of Rotometals Superhard. Assuming the ERS started out at 5.9% antimony, that should increase it to 8% antimony. For convenience, I'm going to nickname this double-enhanced reclaimed shot "DERS". I'll update this post as the data rolls in.
Density = 2719 grains per cubic inch, compared to 2768 gr/ci for J.R. brand shot.

Density is helpful when evaluating an unknown alloy because it lets you estimate the percent pure lead. The 2719 density tells us that this double-enhanced shot is about 91% lead and 9% something else. That's reasonably close to the estimated value of 8% antimony. Possibly it is actually 9% antimony, or possibly it is 8% antimony and 1% various other trace metals.
After 1 day: 43.6 BHN / 10mm, 32.1 BHN / 4mm

The 4mm test seemed suspiciously low so I went back and remeasured it two more times and came up with 32.0 instead of 32.1, woopeedoo. The reason I report both the 4mm and the 10mm test is it's a general trend for a 4mm test to read less than a 10mm test above 21 BHN. Below 21 BHN the 4mm & the 10mm read pretty close. I've yet to explain why the two tests diverge above 21 BHN so I report both and let the reader decide what it means. :lol: The 10mm test is closer to being "official" and its bigger indentation is far easier to measure, so I consider the 10mm test more reliable.

The closest thing I have to a theory explaining the 4mm / 10mm divergence is that the 4mm indentation is so small on harder alloys that it's effectively measuring the hardness of the "skin" while the 10mm test still penetrates past the skin. I can't understand why the skin would be softer than the core, but if for the sake of argument the skin were softer that could explain the 4mm test's lower numbers.

After 2 days: 43.0 BHN / 10 mm, 39.9 BHN / 4mm

As usual I made 2 indentations with the 4mm tester, and as usual both indentations measured the same, so the 39.9 BHN result was not a fluke.

After 3 days: 43.1 BHN / 10 mm, avg. 40.1 BHN / 4mm

This time the two 4mm indentations were different, one scored 36.5 BHN while the other scored 43.8 BHN, for an average of 40.1 BHN. Consider that there was only 0.0032" difference between the two indentations and you can appreciate why the 4mm BHN numbers can be noisy.

After 4 days: 39.7 BHN / 10mm, avg 37.7 BHN / 4mm

One 4mm indentation scored 33.8 BHN while the other scored 41.7 BHN, for an average of 37.7.

After 8 days: 40.9 BHN 10mm

After 2 weeks: 42.1 BHN / 10mm

Average of all 10mm tests for the first 2 weeks:
42.1 BHN

Re: Enhancing Reclaimed Shot ?

Posted: Sat Sep 30, 2017 10:02 am
by mtngun
Well, I'll continue to collect data on the DERS for a while, but it looks like it is going to stabilize at 40 - 43 BHN. That's only 2 - 4 BHN harder than regular reclaimed shot, hardly worth the extra expense. :cry:

I've been thinking hard about why my first batch of ERS was 45 BHN while the second batch was 39 or so. :geek: Here's an idea -- I commonly use rainwater to quench the bullets, from a barrel that collects rainwater from the shooting shack roof. In the summer the rainwater is warm and in the winter the rainwater may be near freezing, but I have been indifferent to the water temperature.

Well, looking back at my notes, that 45 BHN batch of ERS was heat treated around November 30. As usual, I did not pay attention to the temperature of the water that day, but it is entirely possible that the rainwater would have been cold at that time of year. If so, maybe cold water is a necessary ingredient to make 45 BHN bullets? :shock: :o :?

It is not a new idea to use ice cold water to quench bullets, other people have been doing it for a long time and claiming it makes a difference. For example, Wiljen reported a 4 - 6 BHN increase by using a cold quench.

It is about time that I experiment with a cold water quench. For now I will keep it simple and use ice water. I'll try it with regular reclaimed shot, ERS, and DERS.

Re: Enhancing Reclaimed Shot ?

Posted: Mon Oct 02, 2017 7:39 am
by mtngun
Heated to 470F, then quenched in ice water, measured with 10mm / 149kg test. I'm not going to bother with the 4mm test because it is too noisy above 25 or so BHN.

After one day:
JRRS = 40.1 BHN
ERS = 42.0 BHN
DERS = 43.5 BHN

After 2 days:
JRRS = 40.7 BHN
ERS = 45.4 BHN
DERS = 41.2 BHN

After 3 days:
JRRS = 39.0 BHN
ERS = 41.8 BHN
DERS = 40.5 BHN

After 7 days:
JRRS = 40.9
ERS = 40.7
DERS = 44.2 BHN

After 14 days:
JRRS = 38.2 BHN
ERS = 40.8 BHN
DERS = 40.3 BHN

Average for first 14 days:
JRRS = 39.8 BHN
ERS = 42.1 BHN
DERS = 42.0 BHN

-- an ice water quench did not increase hardness.
-- ERS increased hardness by 2.3 BHN, but DERS was no harder than ERS.
-- peak hardness happened after aging for 2 - 7 days.

Re: Enhancing Reclaimed Shot ?

Posted: Tue Oct 03, 2017 11:35 am
by mtngun
Re: adding sulfur to reclaimed shot:

When I experimented with adding sulfur to "super-wheelweight," sulfur boosted hardness about 5 BHN. That suggests that wheelweight does not contain the optimal amount of catalyst.

However, I never did a separate comparison test for adding sulfur to reclaimed shot -- my ERS alloy added both sulfur and antimony, so any hardness increase might be due to the antimony, not the sulfur. In any event, ERS and DERS do not seem to increase hardness much compared to ordinary reclaimed shot.

It may be that reclaimed shot, presumably containing more arsenic than wheelweight, may already contain sufficient catalyst and does not benefit from additional catalyst in the form of sulfur.

Re: Enhancing Reclaimed Shot ?

Posted: Tue Oct 03, 2017 2:57 pm
by mtngun
I found some test slugs of ERS left over from the 2016 alloy shootout. After aging 10 months, it scored 34.2 BHN (10mm / 149 kg). That compares to 32.6 BHN for straight J.R. brand reclaimed shot that aged 10 months, or a 1.6 BHN increase.

It appears that, in general, my ERS recipe increases hardness 1.6 - 2.0 BHN compared to straight J.R. brand reclaimed shot. Individual tests are sometimes as high as 45 BHN but that may be due to measurement noise because if you do a lot of tests, the average is less than 45 BHN.

My DERS recipe appears to increase hardness 3.0 BHN, if even that, compared to straight J.R. brand reclaimed shot.

Those are small improvements that could easily be explained by the higher antimony content.

Just to be sure, I'll eventually test J.R. shot plus sulfur. My guess is that the sulfur will not increase hardness because shot already has an adequate amount of catalyst.

It seems that reclaimed shot is already close to optimal for heat treating. If there is some modification or trick that can substantially increase its hardness, I have not found it. :(

By the way, for measuring hard alloys I have settled on the following technique with the 10mm / 149 kg test. I measure across the indentation vertically, horizontally, and at 45 degrees, and take the average of those 3 measurements. The 3 measurements are rarely exactly the same because sometimes the edges of the indentation are rough, or sometimes the indentation is slightly oval.
Taking the average smooths out those errors.

For softer alloys, this method may be overkill.

Re: Enhancing Reclaimed Shot ?

Posted: Wed Oct 04, 2017 1:08 pm
by mtngun
-- ordinary reclaimed shot peaks at 39 - 40 BHN (10mm / 150kg) after about 2 days.
-- shot probably already contains an optimal amount of catalyst so adding sulfur is not effective, though I have yet to do an apples-to-apples test for that.
-- increasing the antimony to 5.5% - 8% produces a peak hardness of 41.5 - 43.0 BHN, not enough improvement to justify the expense.
-- an ice water quench showed no measurable improvement over room temperature water.
-- even with the best equipment, BHN data is going to be noisy at 40+ BHN. Take multiple measurements of multiple samples.
-- if there is a way to substantially boost the hardness of reclaimed shot, I have not yet found it.
-- while increasing antimony did little for hardness, it did improve fill. DERS cast better than ERS which cast better than plain reclaimed shot. People often talk about adding tin to improve fill, but apparently antimony is also a fill enhancer.

Re: Enhancing Reclaimed Shot ?

Posted: Thu Oct 05, 2017 3:59 am
by Brad
Have you ever tried any of the alloys with small amounts of copper added? If so, did you see benefits.

Those are some might hard bullets you are shooting. How much tin?

I enjoy reading this stuff. Someone going outside the box and doing something new and unusual.

Re: Enhancing Reclaimed Shot ?

Posted: Thu Oct 05, 2017 6:57 am
by mtngun
Brad wrote:Have you ever tried any of the alloys with small amounts of copper added? If so, did you see benefits.

Not on purpose, but I did unintentionally end up with a pot of copper-contaminated wheelweight after the pot's heating elements burnt through the steel liner and came into direct contact with the lead. It made the wheelweight cast poorly, something that has been noted by others who have experimented with adding copper. I never checked to see if the copper changed the hardness. There are some vague reports on the Boolits forum that copper does improve hardness, but their data was extremely poor quality when I read it a year or two ago.

I have not pursued adding copper because the poor casting qualities would never work with the Loverider designs that I favor.

How much tin?

No tin. I have no use for the stuff.