Finding a way to get hard PC'd boolits from regular COWW alloy

BHuij

Active Member
Just put my order in the mail for a copy of Jacketed Performance with Cast Bullets. Probably high time I finally read that one.
 

GRMPS

Active Member
I just use a harder alloy like monotype if I want a higher bhn my monotype tested at:
Smelted Monotype Tested
Pb = 72.0%
Sb = 17.6%
Sn = 9.4%
Cu = 1.0%
 

JWFilips

Well-Known Member
waco,
A pound cast in an old mauser or other Mil Surp is easy for me to do. Granted it takes a few belts of good Bourbon to get the courage to pound the crap out of a hunk of lead in the throat of a fine rifle!;););)
Jim
 

GRMPS

Active Member
That's why many prefer brass rods opposed to taped steel rods. I find that If you used several different length rods in the process you have less chance of flex/damage to the barrel mouth
 

popper

Well-Known Member
Started a new experiment yesterday, soft nose hard body PC bullet. Cooked WW alloy PCd and then placed base in shallow room temp water for fast 15 count. Did vice smash test with another totally AC and base appears to be harder, soft nose. More tests to do.
 

GRMPS

Active Member
Interesting concept popper, you could try 1/4 or? thick piece of ice the base would melt a hole then the ice/cold should not affect the top of the. boolit.
 

Ian

Well-Known Member
If you want the bases harder after the whole bullet normalizes, quench the nose instead. You read that right.

Final results will take at least a week with straight ww alloy. Base quenching only works well if the noses are in a heat sink that soaked at heat-treat temperature along with the bullets. For some reason, 45 minutes is pretty much a minimum soak time for a solid heat treat in my experience. You can anneal them almosr instantly, but getting them hard again takes time.
 
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popper

Well-Known Member
quench the nose instead OK lost me there. There is process for WD where you place in a pan of water, then run a torch across the nose to anneal. Torch will burn the PC. I cooked these for hr @400, pulled one directly out and base into water - for a short time. Thinking suck the heat from the base quick but thermal conductivity of PB should keep the nose warm for AC. These are 170ish gr. RD style. The nose was still hot to my fingers.
 

Ian

Well-Known Member
It don't work the way you think it does.

I did a bunch of tests just like yours and the quench sucked the heat out of the noses so fast they actually got harder than the bases. What happens is the heat is sucked from the nose into the base and then into the water, and the base stays hot longer, making it in effect cool slower than the nose. Hence harder noses. The longer and more pointy the bullet, the worse the effect.
 
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JWFilips

Well-Known Member
Just a stupid question: Does hardness matter after applying PC?
It seems I have shot normal PC coated BHN 12 bullets at 700 to 2000 fps with no difference in performance nor any type of fouling!
 

fiver

Well-Known Member
PC allows you to get away with softer alloys up to a point.
I'm betting Popper is playing closer to the 24-2700 fps zone though.
 

Ian

Well-Known Member
PC allows you to get away with softer alloys up to a point.
I'm betting Popper is playing closer to the 24-2700 fps zone though.
I haven't found the failure point yet in preliminary testing, usually I run out of pressure headroom first. 12 bhn to nearly 3kfps in the .223 and 10.4 to 2400 so far with just one try in .308. The alloy still has to be right (can't be too brittle, or too mushy with tin) but it can be a damn sight weaker than would ever work without the coating and shoot like "RPM what?"

I WILL get back to my quest for speed and accuracy with pc bullets and hopefully be able to make more assertions about same, but other projects in the Empire need attention right now.
 

358156 hp

Well-Known Member
It don't work the way you think it does.

I did a bunch of tests just like yours and the quench sucked the heat out of the noses so fast they actually got harder than the bases. What happens is the heat is sucked from the nose into the base and then into the water, and the base stays hot longer, making it in effect cool slower than the nose. Hence harder noses. The longer and more pointy the bullet, the worse the effect.
All true. I went as far as to do this with double-ended wadcutters as a litmus test, half with sprue up, and half with sprue down so I could test bullet hardness on the ends of the bullets without having the sprue cause erroneous readings. It came out this way every time unless I used my steel heat sink to keep the noses hot longer. I did not try my heat sink on pointed bullets because there was too much air space at the heat sink, and I felt that would give erratic readings. In short, the temperature travels from hot to cold, starving the hottest end of temperature first, and rather quickly. I later found this to be the second law of thermodynamics.
 
Reactions: Ian

fiver

Well-Known Member
weird that's how brass annealing works too.
you'd think some smart guy would write up some kind of physics paper and name it [insert name here]'s law.
 

BHuij

Active Member
My experience has been that heat treating and quenching COWW bullets still gets me better results than shooting them at "base" alloy hardness of around 12 BHN. At least with my .223 through the AR. I never got anything to group as well at 12 BHN and upwards of 2k FPS as I have at 30 BHN and high velocity.

Then again, my ".223 in AR" tests are a well-known clustercuss as is, so you may want to disregard my results...
 

Ian

Well-Known Member
Dan of Mountain Molds liked his coated bullets to be glass-hard, too, and has the years of thorough research published to show why. I dunno, I never shot 35-bhn cast bullets in my life, nor have any desire to do so when 2% Sb/.5%Sn air cooled work fine and shoot the same for me as water-quenched or 3%Sb/2%Sn. It ain't how you do it, it's the way you do it; in other words, loading technique.
 
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Ian

Well-Known Member
weird that's how brass annealing works too.
you'd think some smart guy would write up some kind of physics paper and name it [insert name here]'s law.
It's a good thing the Oehler 35 doesn't have temperature inputs or it would already would have happened. A name other than the "Second Law of Thermodynamics", of course, which it already has had for a couple hundred years thanks to other guys we've all heard of named Kelvin and Joule and so forth.
 

popper

Well-Known Member
OK, now understand what you are saying. As quenching is due to the rate of cooling the real question is at what temp the hardening occurs. My 175gr bullet has ~ 3BTU @ 400, thermal conductivity is 20 (pretty low), so how long with the base on ice to harden the base? My calc say about 2 sec.