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Copper plating onto lead bullets

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Q. We have recently started copper plating lead cast bullets up to 100 µmeters in a cyanide copper bath. We are having a problem with the adhesion of the copper on the lead. The process that we are using is as follows;

hot soak at 60 °C in HP-10
electro clean at 60 °C in HP-15
rinse
rinse
pickle in A-720 (fluoride based acid)
rinse
rinse
plate in cyanide copper at 60 °C
rinse
rinse
passivate in MS-020 (chromic acid)

I would appreciate any comments or advice.

Martin Swart
bullets - Zaire


A. Just a wild guess to get things started, but have you checked to make sure you are not dragging hexavalent chromium up and down the line in cracked rack coatings, or improperly rinsed barrels, or routing chrome rinsewater into the preplate rinses?

I am assuming that your supplier set you up with the preplate cycle, it looks OK except for:

Are you using a copper strike? A hot, full strength copper cyanide may not give you perfect adhesion without a strike.

How are you testing adhesion? (Do you have to work very hard to see the adhesion problem)

Tom Pullizzi
Falls Township, Pennsylvania


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A. It seems to me you are going from an acid almost directly into a cyanide solution. This will cause problems. We immersion clean, rinse, rinse, weak fluoboric acid rinse, rinse, rinse, weak sodium cyanide rinse, rinse then into the copper. We don't passivate. We don't strike in our barrel operation and I assume you are barrel plating.

David Guleserian
- Rhode Island


thumbsup2Great help, David. Thanks!

Regards,

pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey



thrashing

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Q. Can anyone offer any information about plating onto lead. Obviously, adhesion seems to be the biggest problem.


David Grimes
plating company - Farnham, Surrey, United Kingdom

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A. Hi David. I found a reference to ASTM B319 [link is to spec at TechStreet], "Recommended Practice for Preparation of Lead and Lead Alloys for Electroplating".

pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey


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A. A number of years ago, I was involved with a project for the copper plating of lead bullets. I don't remember all the details, but the use of a fluoboric acid dip (followed by appropriate rinsing) was very important in obtaining good adhesion of the copper. Copper was a cyanide based process.

Trust this helps Ken Lemke

ken lemke Ken Lemke
Burlington, Ontario



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A. Hi David ,

Ken Lemke is right, the use of 5% fluoboric acid as an acid dip prior to a Cyanide Copper plate is most important to achieve good adhesion on lead based products; you cannot use either Sulfuric or Hydrochloric acids because the lead salts of both are insoluble.

Best regards


John Tenison - Woods
- Victoria Australia


June 1, 2008

A. I have worked with lead and plated without cyanide copper plating and directly plated to bright acid copper, it works successfully, but should carefully and quick dip with current connected to hanger always, and acid dip with HNO3.

Makk Safna
- Gresik, Indonesia



Plating pistol bullets

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Q. I run a small company that makes hard cast hand gun bullets for hunting and I would like to learn how to apply a copper plating to them to get rid of the problem of leading the bore. I need a process that will apply the copper to hundred's of bullets at a time and will not beat them up or distort them in anyway. Also it must be put on in a way that the plating won't strip off in the riflings of the bore under the extreme pressures of the bullet passing at high velocity. I know it can be done as another company does it to their bullets.

Thanks,

John Anderson
- Andalusia, Illinois


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A. Match Grade 308's? I prefer 300 Mags on a windy day, and 25-06 on a hot calm day. I've shot those rounds and the Copper still comes off in the rifling. In order for the rifling to function it must gall the bullet surface, and in so doing some of the copper is transferred to the rifling lanes. You can analyze the cleaning patches for copper and find it there. Anyway I recommend barrel plating in a finer media such as BBs. If you are really concerned you can use a rotating kiln design. This would virtually eliminate any distortion of the surface, then screen separate them. Fluoborate process. I used to barrel plate Cadmium with a Chromate conversion coating onto 20mm rounds for the navy without media and they still shot as true as 20mm can shoot.

Dave Kinghorn
     Chemical Engineer
SUNNYvale, California



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A. John,

Many years ago I worked at an ammunition company. They manufactured ammo of most common cals. They used a tumbler barrel plating process in very hot potassium cyanide plating solution. I remember the two main hassles they had,were with the antimony content of the lead, causing passivity during chemical cleaning. So be sure of that and work back. and the absolutely critical level of free cyanide in the copper strike bath. That's how they did it.

Mark Gunn
- NSW, Australia


February 11, 2009

A. Hi I am not a engineer but I have been experimenting with a small drum plating setup for my personal use on 45 acp and 45 70 with mixed results not having access to cyanide I have focused on an acid type plating bath (copper sulfate / sulfuric acid). My plater handles around 400 rounds at a time and while not the best bullets I have seen it does turn out usable plated bullets. The drum plater itself works great but I am not happy with the rest of the process but I am still learning. Bonding to the lead is not what it should be, and the plating is somewhat brittle. May try annealing after plating. Also I am casting from wheel weights, and other elements in the lead may be affecting the copper-lead bond. Also need to work on the pre-plating preparation. My first batch I washed in sodium hydroxide solution and got very poor bonding; plain hot water worked much better -- may try phosphoric acid wash next. I will email you pics of the plater if you wish; it would be easy to scale up to a larger size if needed. Don't be afraid to experiment!

mark dula
- stony point, North Carolina



thrashing

Hard plating of cast lead bullets

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Q. Sirs:

I am a small cast lead bullet manufacturer looking for an edge and better sales. Copper clad bullets are not the best, pure copper over lay on bullets peels off at high velocity and leaves too much fouling in the barrel. Iron would be harder and with a carnuba wax final polish would be a distinctive dark color and do the job. Questions? Can lead bullets be barrel plated with iron? They come out of the caster clean with no oxide coating to be removed. What chemicals would be needed, what basic plating equipment would work? Process question- I use cement mixers in a Teflon polymer coating process now, can they be used with modifications to barrel plate? I have a complete machine shop and can make almost anything. Please return your thoughts and suggestions.

Thank you,

Peter Wilbur
- Lincoln University, Pennsylvania, USA


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A. Most job shops do not know how to properly prepare lead for plating, therefore the plated deposit has poor adhesion and "peels" off easy.

The process should be: Alkaline clean off the "organic soil", rinse, dip in 10% Fluoboric Acid. rinse, strike in a Copper Fluoborate Plating Solution, Rinse, Copper Plate in a Copper Sulfate Solution to thickness desired.

Proprietary Hardeners are available from companies listed on finishing.com that will work in the copper sulfate solution.

One of the problems you may be having with your current copper sulfate solution is that fact that lead removes the 50 ppm of Chloride that is necessary for the Copper Sulfate Solution to work. By first striking in a lead soluble solution you will cover the lead and then the sulfate solution only "sees" pure copper.

Robert H Probert
Robert H Probert Technical Services

Garner, North Carolina

Editor's note:    
   Mr. Probert is the
   author of



June 21, 2014

Q. I am looking to set up to plate lead bullets. The bullets that I plan on plating are .9 Square inches. I am trying to find out how many amps and volts I would need to barrel plate them to a thickness of .005" if I were doing 1000 at a time? Also, I am wondering if I were to plate say 2000 at a time would that be as simple as doubling the amps or is it much more complicated than that?

Ryan Wooton
- Medford Oregon USA
  ^- Privately contact this inquirer -^

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