Heat treating 3.5/3.5/93 alloy?

[andym79]

How much is heat treating a 3.5/3.5/93 alloy to 430-450 and quencing it likely to harden the alloy up?

I tried an alloy with a high antimony content in my M96 and when I drove it too hard it clean striped and was missing the target. The 3.5/3.5/93 alloy however just tipped to a varing degree in flight!

I assume a bullet harden by heat treat will behave differently from one that is hard due to a lot of antimony!

[williamwaco]

You should forget about heat treating and concentrate on load development.
That alloy is plenty hard "as-is".

[runfiverun]

the 3.5% tin is going to limit your soak temp.
you'll get into the 390-f area before it slumps.
anyway getting them there and holding them there for about 15 minutes [depending on the mass of the boolit to let the heat soak into the boolit] then dumped into ice cold water will give you a bhn of about 25-28 or there-abouts.
I'd actually cut that alloy in half with soft lead and then heat-treat it at the higher temp, you'll be able to get the same hardness without the tin affecting you near as much.

your assumption of the alloy's acting differently is correct.

one more thing that would help is cutting your alloy then crossing that with some ww alloy to lower the tin content even more, but adding some AS [arsenic] to the mix and gaining a little antimony back in the process [shoot for about 2-2.5%] will also help you.

[andym79]

the 3.5% tin is going to limit your soak temp.
you'll get into the 390-f area before it slumps.
anyway getting them there and holding them there for about 15 minutes [depending on the mass of the boolit to let the heat soak into the boolit] then dumped into ice cold water will give you a bhn of about 25-28 or there-abouts.
I'd actually cut that alloy in half with soft lead and then heat-treat it at the higher temp, you'll be able to get the same hardness without the tin affecting you near as much.

your assumption of the alloy's acting differently is correct.

one more thing that would help is cutting your alloy then crossing that with some ww alloy to lower the tin content even more, but adding some AS [arsenic] to the mix and gaining a little antimony back in the process [shoot for about 2-2.5%] will also help you.

Okay so next time I make up an alloy of TIN, Lino and Lead, go a lot easier on the tin, in fact perhaps just use LINO and LEAD? So its the antimony that the heat brings to the surface to harden? Isn't it the tim that helps with good fill out?

So I should give heat treating a go at 375F?

[runfiverun]

tin breaks the surface tension allowing the antimonial dendrites to push through the surface of the alloy and fill in the corners of the mold.
however if your tin content goes above about 2% [in this case] it will start to puddle on the surface of the boolit giving the boolit a spotted affect [it's why boolits with high tin content are shiny] on the surface.

if you use lino and lead a 3 lead to 1 lino will give you a 1% sn and 3% sb alloy you could cut it down to 4 to 1 giving you a good mix also.
the arsenic in the ww's or in magnum shot is a good thing to have also about 0.20% is a great grain refiner and it also helps the antimony migrate and acts as a "catalyst" when heat treating [quenching actually]
tin in lower amounts .25% and down the about .0125 % or so will also act as a grain refiner in the alloy.
sulpher will also do the job of arsenic and as a bonus it will help pull zinc from the alloy.... if you don't want it in there [shrug]

I'm assuming you are trying for some higher velocity loads here.
so i'll give you a couple of hints of how to make it happen.
the first and most important rule is to get the boolit started inline with the centerline of the barrel.
then you must have a good static boolit fit.
then do no damage to the boolit launching it into the barrel and accelerating it down the barrel.
finally down the list a bit is your alloy.
I use 2 main ones 4/6/90 and ww alloy cut with 25-30% soft lead with .5% tin added then water quenched.
after the quenching I wait a month before using the boolits and quite often 6-12 months pass before they are shot.
and load selection is about here in the line-up.

[grouch]

I use ww + 2%tin water dropped from the mold in my '96, and get decent to extremely good results, depending on the alignment of the stars and the other crucial factors - anything from 5/8" at 100yds(stars aligned once or twice over a 15yr period) to 1 1/2" most of the time to 2"+ when it's really not my day.
Remember you're dealing with a very fast rifling twist - your velocity will likely not be as fast as you'd expect from a slower twist barrel. Try loads of medium to slow powder(4895, 4064, H414) starting at velocities 1400 - 1500fps, and work up 'til you see results.
Good luck, '96s can be picky about bullet choice, and generally not very forgiving in terms of cast bullet accuracy.
Grouch

[williamwaco]

Runfive +1

I try to keep tin over 1% and less than 2%.

1% is enough to cast good handgun bullets ( which is 99% of my casting ) and anything over 2% is wasted and tin is VERY expensive.

[bangerjim]

YES.......... at the price of Sn these days.......................1-2% is definitely more than enough!

I keep mine at 1% or slightly higher with excellent fill results.

And a HOT HOT HOT mold!!!!

bangerjim

[andym79]

If I don't need more than 1-2% tin then I will definetly mix up another alloy soon.

[fivel_976]

Vary helpful