Hollow point alloy guidance.

[Michael J. Spangler]

I was hoping for some guidance to select a proper alloy for this 45-70 bullet.

It’s an MP 462-420 with the Penta pin installed. The alloy was XRF scanned at about 1.6% antimony and no tin at all which amazes me after what I mixed up to get to it but that’s another thread.
So I added a fair amount of solder to the pot to get good fill out. Probably not as much as I thought I added.

I figured this was the easiest HP style to get to expand. I was right 😁
I was pushing them about 1550 FPS. Well they tore back and shed the petals leaving just the bottom two driving bands.
They flew clean through 16” of ballistic gel and were caught in a box of rags I used as a backer.

I’ll probably load the rest of them over 12 grains of unique figuring that would give some pretty looking expanded bullets just to have something to look at while I work up a proper alloy.

However the whole point of this it to find an alloy that will work for a 1500 FPS or so load and hopefully not tear apart.
Is that possible? Am I just way shy on the tin? Should I run more antimony?
I also going to try the cup point and the regular hollow point with this same alloy.
I’m hoping the smaller hollow will hold together better.

If the Unique load works well I might just load up a bunch for a buddy for his light loads for whitetail. My guess is. 405 at 1100 will drive clean through a whitetail.
This same alloy and scaled down Bullet design in a 38 at those speeds mushrooms beautifully.

Thanks all for the advice!

[Forrest r]

You'd be better off using a cupped hp at those velocities.

The watered down version:
1bhn for every +/-100fps of velocity the bullet has

an article from may-1953 with different hp's and the alloys they used coupled with how they performed at different velocities.
http://www.goodrichfamilyassoc.org/4...20rifleman.pdf

I've done testing with these 44cal hp's in 2 1/2", 4", 6", 6 1/2" & 10" bbl'd 44spl and 44mag firearms.
[IMG][/IMG]

The penta hp's did their best in the 800fps range with 8/9bhn alloy. 1000fps was pushing the limits of the hp design
The large hp's did their best in the 1000fps range with 8/9bhn alloy.
The small hp did their best in the 1200fps range with a 11bhn alloy (ww's + tin)
[IMG][/IMG]

The performance of your hp's depends a lot on the hp design. Different hp's for the 38spl & 357's. The top row 2nd from left is a mihec 640 bullet that has huge penta & round hp's. They ok for snubnosed 38spl's but will never hold up to the hv 357mag loads. The bottom row center bullet is the cramer "hunter" bullet that has an extremely small hp and holds up to +/- 1200fps hits.
[IMG][/IMG]

Bought this 432-gc mold to do testing with lighter bullets in the 44mag/10" contender.
[IMG][/IMG]

The only hp that would hold up to hv 44mag loads was the cupped hp that were cast out of 11/12bhn alloy and then the bullets were pc'd and sized.

I'm sure others will chime in

[Larry Gibson]

As mentioned, the Penta HP is probably not the best choice for that velocity. Also you might try 16 - 1 alloy (Lead - tin) with no antimony.

[Soundguy]

IMHO.. I don't like bullets that shed fragments... I'd prefer to keep the mass and have it mushroom intact.

[Michael J. Spangler]

Thank you all.
So keep the penta to 1000 FPS or so? There’s now way to toughen it up enough to hold together for that type of speed?

I’ll cast some of the standard HP and some of the CUP to try out for the next range trip.
Sounds like the cup might be the best hunting option.

[charlie b]

Also keep in mind that you need to test at the terminal velocity. So, whatever range you expect to shoot at, determine that velocity. Down load some bullets to that velocity and test expansion.

PS I would also go with what others have said about more tin in the mix and smaller HP for higher vel.

[Soundguy]

what bhn are you running it? depending on allow you should be able to get it hard without being brittle. Tin / lead bullets seem to obturate and mushroom nicely without fragmenting. a lead/tin bullet with just a HAIR of antimony might be the ticket.

[Michael J. Spangler]

Good point on the terminal velocity.
I won’t be hinting with them in this stupid state but my buddy will be in Maine. His shots aren’t much over 50 yards so he won’t be losing much speed at all but it’s a great point to keep in mind.

I’m guessing the brinell is around 11 or so.
Are you thinking popping a pound of 60/40 in the pot and getting it up to about 3% tin might help? Or is that too high?

Hmmm I also have some lead free solder with copper in it. I hear that adds some nice toughness.

[Soundguy]

The copper will harden the bejeebers out of it but we'll make it tougher personally I would bring the 10 percentage up and if you're adding 10 and Lead that will also make the antimony percentage go down and I think that combination will actually build you a good result with a bullet that isn't blindingly stiff but probably will retain its weight and not crumble or shed pieces

[fredj338]

LHP expansion is about alloy & HP design. If you want good expansion @ higher vel without losing mass, you need a cup point imo. The Penta points are great for low vel expansion & 20-1 lead/tin works great to about 1000fps. I have also used range scrap w/ 1% tin. When you want to go go to 1500fps, you can use the same alloy in 45-70, but you want a cup point not a deep, fluted HP.

[downzero]

Now you guys have me nervous. I am planning on using my normal alloy, which is 1/2 stick on and 1/2 clip on wheel weights for my deer hunt this fall. I'm using the Lyman mold and I worry I may want something harder.

The deer are tiny compared to the midwest out here in the west, though.

[Shuz]

Now you guys have me nervous. I am planning on using my normal alloy, which is 1/2 stick on and 1/2 clip on wheel weights for my deer hunt this fall. I'm using the Lyman mold and I worry I may want something harder.

The deer are tiny compared to the midwest out here in the west, though.

If you're using the Lyman 429640 your alloy will be fine if you add 1 to 2 percent tin .Ive used that boolit and alloy with great success in the. 44mag at 1000 to 1100 fps.

[megasupermagnum]

I mean, unless I were hunting moose, I think that is beautiful for anything else in Maine. There's nothing wrong with that bullet as-is other than it isn't pretty like a flower.

For alloy, zero antimony is ideal. The fact that those held together like they did tells me you are just fine. You only want to add tin to make them tougher.

My advice is if you have multiple pins, use the smallest one you have. That alone will probably fix this.

[Stuckcase]

20 to 1
Coat the bullet
No water quench
My best recipe for expansion—staying in one piece

[Michael J. Spangler]

Ok swapped out for 1 cup and 1 round hollow point with the same alloy. I’ll probably pop some more tin in the mix before I cast them up. Maybe not. One variable at a time.

I’ll run a handful like this and test with the same load.

Before the mould cools off I’ll probably refill the pot and make sure I’ve got a solid 2% tin or so and maybe a little more antimony. Then I’ll cast up some more penta pins and see how those bad Larry’s do at 1500.

[megasupermagnum]

No, don't add any antimony. The only time you would want to add antimony to a hollow point is if you want to make varmint style bullets that grenade, or simply want to blow up some water jugs. As you say, one variable at a time. From what I see, your alloy is pretty good as it is. More tin might help, maybe not. Antimony will definitely make things worse.

[Michael J. Spangler]

Got it.
Cast some cup and round as is. Added approximately 2% tin and cast some more cup and round.

I’ll test both of these side by side to see if the extra tin did anything or not.

[gwpercle]

You don't want any antimony ... this is where the brittleness comes from .
Use a simple tin / lead mix .
For Hollow Points Elmer Keith suggested : 1 / 20 tin-lead mix .
or depending on velocity ... a 1 / 16 tin-lead mix .
You are going to have to find the velocity - alloy sweet spot , but that's why we cast & reload .
Also you want to air cool the boolits ... do not water-drop or heat treat them . You want them tough and malleable not hard and brittle .
Gary

[farmbif]

there's lots of great info here but I found that the detail of hollow point cast bullet information that glen fryxell goes into in his book is extremely thorough and how he explains how each bullet and alloy actually performs while hunting all sorts of animals makes it a must read if you really want to know
it a free download at LASC

[Michael J. Spangler]

Ok I said screw it and mixed up some 16:1 in the little cast iron pot.
I cast up a bunch of each hollow point style so now I’ll have test loads both fast and slow in a
16:1 and another alloy with about 1.5% antimony and 2% tin.
That should tell me a lot and show me which direction I need to go in.

I probably should have shot some before making more but I can’t sit around on a nice day and let that beautiful new mould lay neglected on the shelf.