Zn/Cu alloy

popper

Well-Known Member
Test to see why BLL on PB doesn't work at higher fps. HiTek coated bases, then Bll. GCd BLL works, PB doesn't. Even have a couple sans GC to try. Not expecting a lot of accuracy but hopefully no gas cutting/leading.
 

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popper

Well-Known Member
Some more tests with 30/30 & soft alloy. 170gr PB base HiTek coated, Bll lubed (a couple 185GC bare too). 50 yds, first shots were 170PB coated base, did OK, then leading set in. Also a few 185GC with BLL shot OK. Fps in the 16-1800 range with 2400. My conclusion: the alloy works PCd or GC and HiTek base coat does it's job but alloy by itself strips/gas cuts. Confirms my thought that gas cutting will blow the BLL off soft alloy. Managed to 'accidentally' put one rnd between 2 touching 2x4s, bored through the edge on one and spit the dickens of the other. When they hit the berm - big cloud of dust - hard alloy makes just a small 'puff'. Leading isn't terrible but obvious. I'll up the Cu & Zn next batch to see if the alloy works a little better.
 

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fiver

Well-Known Member
I think you can bump the Zn if you don't have other stuff in the alloy up near 2 maybe 3%.
I'm not sure how it's reacting to the Cu though.
your gonna get to a point where your alloy temps are up real high and then finally see a sheeting action under the spout.
 

popper

Well-Known Member
In this heat & humidity my casting sessions are only long enough to get some good ones to test. Haven't really had any problems so far at normal temp, 725-740F. This stuff is sort of weird. Dropped one from the bench and got a ~0.050" flat spot. Threw a couple as hard as I could and only a 0.2" flat spot on the nose. Hmm?
 

fiver

Well-Known Member
that is odd.
unless maybe the alloy isn't completely staying tied together.
or the percentages are lower than expected.
 

popper

Well-Known Member
After my 2nd cup of coffee, I revisited the stress-strain curves. Yup, non-linear for low stress. Squishy at low psi, then hard up to plastic region, then shear failure. Adding the Zn should stiffen at intermediate psi, Cu should increase the plastic region - both (& Sb) will move the plastic region up in psi. BHN testers make a measurement at the plastic region so are not accurate at low and high BHN.
 

fiver

Well-Known Member
well that could explain some issues with the 40 earlier then.
it would also confirm my suspicions of the alloy being a bit better with the addition of something else to it.
 

popper

Well-Known Member
Cast some from the higher Zn/Cu alloy (1%Zn/0.5%Cu/ <1%Sb), 185GC & 165PB for the 40. Hitek coated the 165, didn't come out right so I added a coat of BLL. Interesting they sized 402 from the 401 sizer that does 401 for isocore. I did notice that 'stringy' effect on the nozzle @ 725F, disappears @740F. Dropped one on the floor and didn't see any dents. Anyway, got the 4 2x florescent ceiling fixtures changed out to LED strip lights so maybe get to test next week. SIL & kids went dove hunting north of Houston Fri, saw birds in the trees so no luck. Guess they missed a few too.
 

fiver

Well-Known Member
the water hole I finally figured out has petered out already.
I been watching it on and off for quite a while now and finally figured out when the birds were coming in.
their numbers decreased 50% every day and last night was horrible.
I got 2 and knocked down 1 more which got up and flew off before I could get to it [looong shot probably 65 yds] I only seen about 6 others come in on the other end.
opening day I got my 10 and lost 1 but could have got a 5-6 more pretty easily after I limited out.
the next day I got 8 and that was about all that come in my shooting area.
I usually only get 1-2 a season so I'm almost bragging and not complaining.
 

popper

Well-Known Member
Think I'm going to like this alloy. Loaded the 30/30 15gr 2400 & 40sw 4.5gr 231. No bulge loading the 30/30. If accuracy is good I'll pump the 30/30 up with leverE. Hard AC so good for HiTek coating, no WD needed. Should be same for PC. IF good I'll send off for an analysis. If I get invited it may get used on some piggys too.
 

Ian

Notorious member
After my 2nd cup of coffee, I revisited the stress-strain curves. Yup, non-linear for low stress. Squishy at low psi, then hard up to plastic region, then shear failure. Adding the Zn should stiffen at intermediate psi, Cu should increase the plastic region - both (& Sb) will move the plastic region up in psi. BHN testers make a measurement at the plastic region so are not accurate at low and high BHN.

Very good perspective on the problem!
 

fiver

Well-Known Member
that low stress mush is hard to think about especially when you increase the stress load and have less deformation.

the alloy make-up is very important but understanding how the pieces interplay under that stress, in the barrel, and on target is more important.
it's super hard to make someone understand how zinc or tin affects their alloy when all they can think of is antimony makes an alloy hard,,, then brittle.
it does and yet it doesn't and it's important to understand exactly how the pieces tie together and affect the lead as a whole or part of the whole, and then again how they react to being moved around under pressure.
it isn't the same.
 

Ian

Notorious member
That's pretty much Dynamics defined. The sudden "softening" as shear planes slip and create heat can work well or poorly depending on when and where it happens and how far it goes. The usual practice of over-building the alloy for the task at hand by using a lot of grain refiners and fine, intermetallic lattice structures works pretty well because you never see a massive shift in alloy integrity during the launch. You sure see it with heat-treated, low-antimony rifle bullets though.

I wonder what precipitation characteristics this 1Zn/.5Cu alloy is going to have?
 

fiver

Well-Known Member
so far it seems to only be an internal bond.
that's why this last iteration had 1% antimony added to it.
I think the Sb will help tie up some of the copper but also add that last bit of hardening agent/strength to help in the initial phases.
 

popper

Well-Known Member
Ok, not too bad. MG 30/30 15gr 2400 185gc @ 50. top 2 are 170gr Sierra FP, don't remember the load. Really had to scrub to get the bore clean before this test. 2nd is 40sw@7yds, top is 180 WWbox, rest are 165gr PB with 4.5 231. You guys got me on what the Zn does with the SB/Cu but it works. Now to use a full tilt load.
 

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fiver

Well-Known Member
that looks much better than anything so far.
the next go around should be the real test, hopefully you get to try it on some pigs too.
I'm guessing at the bhn here,, at maybe an 8 or 9.
but the fluidity of the alloy should be real interesting on a live animal.
 

popper

Well-Known Member
10# pure/4# isocore, ~9 BHN, Bumpo calc. says 0.8% Sb. Going to go ahead and get it analyzed, adjust from there. I shot some a little softer with 33gr of LeverE so don't need to repeat that. With the 15 gr 2400 that should be ~1900 fps, good there. Range has a slot on pistol where shotgun slug shooting is allowed, might get a box of sand to test there.
edit: squished with a 60/40 pure/iso boolit. This alloy was dented by the 60/40 - no dents in the 60/40..
 
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popper

Well-Known Member
Trying to size down for the BO & getting these stuck in the Lee (312 as cast/311/310/309/308). GC or PB. Need to try something other than H2O as a lube. I guess cleaning the sizers in the US is easier than driving boolits out with a punch.
 
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fiver

Well-Known Member
some laundry or dish soap then a wash after would help.
I have to lube the coated ones just to size them down .001 it doesn't take much but it's necessary.
 

Ian

Notorious member
A paste made from Ivory soap and DISTILLED water works too, and easy to clean off afterwards (collander and a spray nozzle on your garden hose)