Differential Heat Treat??

[McMullen759]

Hey all,
maybe this is in here somewhere but I have not come across it in my reading- at least not in any detail. I learned years back about differential heat treating when I got into forging (lot of fun, if you haven't tried you really should). Basically quenching only a part of your blade (or boolit) to have hardness where you need it and softness where it will be of most use. Typically you would aim to harden the edge and keep the spine soft through whatever method you wish. This has me thinking- who has applied this concept to cast boolits? seems there could be some great results by tuning your boolits to behave in a more exact and predictable way for the results you want. For example many go for very hard bullets- great for targets, but could be better for game if softer and these such things.
Ok, ok- I'll get to the point...
Has anyone experimented with this concept in different methods? Here's where my head is at for options:

1) Hard base to allow good grab at high velocities in rifles with soft tip for more of a mushrooming effect/energy dump at impact.

2) Soft base to allow better obturation/seal on firing with hard tip to enhance penetration and having almost a reverse mushroom effect where the tip swages back into the soft base on impact.

Anyone tinkered with such a concept? I'd love to hear what people have tried and how it worked out. I'm planning on trying a few options when I get everything set up for my first batch- water drop and draw back hardness on tip for a small batch, the opposite for another batch (base) and the third was thinking of trying to water drop them but very controlled so as to only get the tip/base in the quench. I'm likely overthinking this but there has to be a "perfect" balance where everything works "optimally" that would be more ideal (even if only marginally so) than trying to find a balance of hardness for the whole boolit where you nust either sacrifice the good shootability often associated with hard boolits for better energy transfer into the meat.

[HWooldridge]

Haven't tried this but I would likely stack a bunch of boolits in a biscuit pan, fill it with water until the bearing surfaces were covered, then hit each one with a propane torch. Heat the first one until the nose starts to slump and back off a couple seconds.

[Dusty Bannister]

It might be difficult to apply ferrous metal techniques to non-ferrous metals. There have been many excursions down that path of making different hardness from the same cast bullet alloy. You can see by the successes written about the virtues, how practical that is.

Some have tried casting a nose from pure lead and the remainder from hard alloy. Again, very labor intensive and weight control has been problematic. One custom mold maker even produced a ladle that only dropped a small amount of lead and the operator then followed with a normal flow of bullet alloy. If you have a plan, go for it, and document it for others.

As Bill Ferguson (the Antimony Man) used to say, "try it and see".

archive search:
https://castboolits.gunloads.com/sho...ng+bullet+nose

[McMullen759]

That's kind of what I had in mind, although for consistency/control was thinking of having them in the pan of water and set in oven/toaster oven to expose only the end to the heat of the element. I've heard of guys using different alloys and that was what got me thinking this method might be the answer to the weight/balance issues as density would be homogenous.

[Dusty Bannister]

Um, that was specifically discussed in the thread I referenced.......

[country gent]

The soft nose casting isnt to bad with the right equipment and set up. I occasionally cast 45 caliber rifle bullets with a soft nose.
I have 2 ladles one is small and holds a measured amount of lead for the nose. The second is a lyman ladle for the base.
My pot is 2 cavities 1 bigger and the second inside it. the inside pot is for the pure lead the bigger outer ring is for the hard lead base.
The small ladle is a tapered end forming the spout. held level it drains to what the nose holds. this is poured in then the ladle of hard lead is poured in forming the sprue.
The 2 alloies solder and blend together. You can see the color difference at the seam.
My small ladle was made from brass round stock drilled and the end cut at 45* with a handle attached. It is sized so that it holds the measured amount of lead.
You want to cast on the hot side.
In use bring the pot up to temp
Pre heat the mould
Pour the nose then as quick as comfortable pour the base and sprue let solidify and cut sprue.
Repeat

The double pot keeps every thing close together. I leave the ladles in the pots and run with them

[gwpercle]

Lyman used to sell a set of moulds ... #1. cast the body , with hard alloy and mould #2 cast the nose of soft alloy ... then you took epoxy glue and glued the boolit halves together after it set up you sized and lubed it ... Wah-Lah ... Hard body - Soft point
problem is it's no longer in the Lyman Catalog ! Oh Well !
Might find these moulds on E-Bay now days .
Gary

[McMullen759]

Whoops, missed the link Dusty. I think that was during the time i was having computer issues and had like 8 tabs on the go. When i get a bit of time i will definitely give that one a read, thanks.

Country Gent that is a great talk through of the process and sounds like you've got a really efficient setup for it. would love to see that in action, sounds really interesting.

Haha The epoxy thing sounds pretty sketchy, like a hillbilly/poormans nosler partition. anyone ever fired one of those into something? My instincts tell me it is unlikely to hold up well and more likely to shed half of the bullet but then, epoxy is pretty tough stuff... hmmm I'm very curious about this now- if nothing else just to know how it worked out.

[McMullen759]

Dusty, just got a look into that link. Haven't had a chance for a proper readthrough but it looks like EXACTLY what I was looking for!! Thank you so much, I'm still getting the hang of navigating/searching the site and not having the greatest of luck with the search function. Thanks again, this is great stuff!

[rintinglen]

I had one of those Lyman "Twofer" 38/357 molds. I think it was a 358-624, but I only had it for about a year and seldom used it. IIRC it was about 1980, but I'll never forget how bad my memory is. But what I plainly recall is that it was a major pain in the butt and not worth the effort.

You had to have two pots, or else, as I did, cast one run of noses , empty the pot and then refill and melt the second batch of harder material for the base. Then you had to sort through, toss the rejects and then glue the pitiful remainder to make a depressingly small number of boolits. IMO, it was a very poor recompense for an afternoon's labor. Then too, they didn't shoot nearly as well as my 358-156 SWC's. And those I could cast 6 or 8 times as many, even with a two-cavity mold. Yeah, a gas check added a whole penny to the cost, but groups were much tighter, there was no difference in expansion in wet news print at 357 velocities, and leading was less. I sold or traded it off a few months later, and wrote that one off as a lesson learned.


For rifle use, take a look at BruceB's comments on how he melted soft lead to make a nose then filled the mold with hard lead. I made a few for my 45-70, and it was time consuming, but effective. As he suggested, you made a few for hunting, then cast as many regular boolits as you needed for practice. I never managed to get Bambi to cooperate so I have no Idea how well they work on game, but the noses were much softer than the bodies were.

[Bigslug]

Just some armchair hypothesizing here...

One technique I've seen mentioned here and there is to plunk a chunk of softer alloy into the nose of the mold and fill the back end with the harder stuff. I suspect a round nose mold that would center and hold an appropriately sized pure lead pellet out of a buckshot mold might be the ticket.

Alternatively, you could use a number of said pellets for uniformity, heat them in a mini-ladle, and pour them into the nose of your pre-heated mold first.

Either seems like a single-cavity mold proposition to me - plenty enough to juggle without having to perform operations for multiple holes.

As to softer base with harder nose, that's the kind of stuff we control with correct bullet sizing, so I'm not sure there's much point.

[Dusty Bannister]

Bigslug might have better luck with a multiple cavity mold to keep the mold up to casting temp. Just not do more than one or two at a time. You could probably see the difference at the merge line of the two different alloys. This would be with both alloys melted.

I did fool with the lead BB in the nose and I suppose if the lead had no oxide coating or graphite coating and was hot enough to allow the two to melt and blend at that point, it might work. I decided to just work with the alloy and not waste any more time on that project.

[JSnover]

The two-part method using two different alloys is probably the best. Lead conducts heat so well, I don't know if half of a boolit could be cooled well enough to not be affected. It sounds simple, cheap, and easy to do, if it's keeping you awake at night (like it would if it was one of my ideas), why not try it?

[Doughty]

About 20 years ago I experimented with the two alloy method using a technique developed by my friend Dan Tyler. It required two bottom pour melting pots. One pot with a soft alloy with no antimony in it. I used 20-1 lead - tin. The second pot had wheel weights in it. Both pots were brought up to a good hot casting temperature. The pre-heated mold was brought up to a good casting temperature by casting bullets with the WW alloy until it was making good bullets.

Now for the technique. The hot mold was placed under the spout of the soft alloy pot then the fill lever was moved up and down just about as quickly as was possible, putting a small squirt of lead into only one cavity. The mold was then immediately moved to the WW pot and filled in a normal manner. A little trial and error would soon have me getting the amount of soft point that I thought I might want. Once the approximate timing was determined I then followed this procedure as quickly as could be done; not taking time to examine the cast bullets. When I had cast a sufficient amount of bullets, I would then sort them. Some would have defects, as when doing normal casting. Some would have less of a soft point than I wanted, some would have more. I started off trying to get the soft point length to be the same as the bullet diameter. After casting, I would then heat treat in the oven and quench in water.

Using this method and technique I was able to easily cast plenty of usable bullets. I was shooting these bullets at around 2400 fps. The ones that fell outside of the desired amount of soft point I shot for practice, saving the chosen ones for hunting. I found very little difference in point of impact. I found that the ones that had too much soft point were good for using on gophers or prairie dogs. It wasn't long before I determined that my choice soft points ruined too much meat in deer and antelope, so I tried the ones with only a little soft point. I didn't like them either, so after a while stopped using soft points altogether. One exception was in the .30-30 at 1900 to 2000 fps. They seemed to increase effectiveness without ruining too much meat, but I could get the same results by just hollow pointing what I wanted with the Forster hollow point tool.

So when all was said and done I was back where I started, but the trip was a lot of fun.

[charlie b]

You went through the same thing we did. Trying different alloys to get good expansion and penetration. Tried duplex alloy loads as part of that. Finally just went to plain HP for most uses. Tweaked the alloy to give expansion at the vel we were shooting. Alloy was different based on what muzzle vel (and range) we were shooting.

When it came to pistols the plain old SWC or large meplat solids worked best on big game. Push with enough velocity to get full penetration.