Core bonding

[just bill]

I've searched the threads about bonding cores. I tried to bond cores to 5.7 converted to .308, after what I thought was the proper way. I tumbled them to remove the residue left by the torch. When I unloaded the tumbled some of the cores had dislodged and also split. Any ideas how to avoid this again?
Thanks,
Bill

[rancher1913]

helps if you use core bonding flux. jacket needs to be at final size. think corbin has a write up for the proper way to do bonding.

[clodhopper]

I've had failure to bond using flux and heating the bullets in an oven.
100% success use the same corbin flux, and heating the bullets quickly with a torch.

[grullaguy]

What method are you using to melt your cores?

[just bill]

Torch.

[M.A.D]

Torch.

Try to find a small pottery kiln, You can pick them up pretty cheap... Little dental enameling kilns are perfect . Great for annealing jackets and perfect for even temperature core bonding .....

[uncle dino]

Direct flame is by far superior to any method that
I have found. I think I've tried them all. Heat the jacket quickly with corbin bonding fluid and your results will be perfect every time. D

[reed1911]

On the flux, a quality acid based flux is necessary and clean, clean jackets. I've always kilned mine, but the torch method seems to work across the board for many others so you need not invest in one unless you need to do enough to get the money out of it.

[M.A.D]

On the flux, a quality acid based flux is necessary and clean, clean jackets. I've always kilned mine, but the torch method seems to work across the board for many others so you need not invest in one unless you need to do enough to get the money out of it.

I've always used Bakers Soldering Flux. Jackets get a Quick wash in Septone Wax and Grease remover .... Ive seen old dental kilns go for $100 , they are usually big enough for 100 jackets

[grullaguy]

I use a torch as well. I use an under weight cast core with slivers of lead added beneath until I get the desired weight. I dip the core in a tub of plumbers paste flux getting just a tiny smidge of flux onto the core. The jacket is held over the torch flame until the lead melts and the impurities and flux come to the top and start to smoke. I then dip the bullet 2/3 of it's length in a margarine container of cold water.

I know everyone has their preferred method, but this works for me.

[firefly1957]

I used acid flux lost a few of each batch to the lead erupting from jacket for some reason ,probably moisture.

Shooting them in .223 I really found no advantage in bonding the core. I did with early ones learn that they had to be cleaned well that flux rusts dies badly!

[midnight]

Corbin recomends rinsing the bonded cores in a baking soda solution. Rinse well & dry and then seat cores to expand jacketed core & then form point.

Bob

[grullaguy]

Yes, I should have mentioned that I tumble the bonded jackets with a 2 tbsps of lemon juice (citric acid), some dish and water for an hour. I then rinse multiple times in hot water to get any remaining nasties out.

[midnight]

I was thinking that since Corbin's flux is an acid, that rinsing in an alkaline solution like baking soda would be the way to go. I can see why using citric acid would make the jacket nice and shiney again and if followed with a thorough rinse would probably work just as well.

Bob

[Forrest r]

I'm sure it isn't the correct way to bond cores to the jackets but I've always used plumbers flux and fluxed the jacket with it (model paint brush). Then I tosses the lead core in and stood them up in a cast iron skillet. I was bonding cores to 9mm and 40s&w cases. Once the cast iron skillet was full I put a piece of metal over it (lid) and put the skillet in my propane grill and turned the grill on high and shut the lid.

Came back +/- 15 minutes later and the lead was melted in the cases. I shut the grill off and let everything cool. Then I gave the bonded cases a quick rinse in baking soda water to stop the acid in the flux.

The thinking behind this was to make a jacketed hbwc for the snubnosed 38spl and 44spl. It didn't matter what I shot with those bonded core bullets. The 9mm and 40s&w cases stayed bonded to the cores. They were actually pretty impressive.

[midnight]

I ordered some of Corbin's flux Saturday. I am making some 416 bullets for a 416 GNR. Hardly worth buying full set of dies for the number of bullets I will shoot so I made a core seat die cuz it's easy & swage cores with the 375 die set. The problem is forming the point. I have a .442 PP point form with a really nice point. It tapers up to a small round nose. It's called the "money bullet". But it's still .442. If I close the tip to about a .125 meplat, the middle expands to .430. If I almost close the tip the middle goes to .442. I made a couple draw dies and draw them down to .4165 but I probably have loose cores. I am hoping core bonding will fix that.

Had a lot of fun making all the dies & punches but maybe I'll just spend the $318 and get a proper point form die from Corbin.

Bob

[Pipefitter]

Are you using "pure" lead for cores? When you bond cores to jackets you are essentially soldering the lead to the brass jacket. Pure lead does not stick well to a brass jacket without a fair amount of tin in the alloy. The inside of the jacket also needs to be chemically cleaned, at the very least use a wire brush to remove any oxides
( look at any youtube video on soldering copper pipe, you will see that even bright shiny copper does not take to soldering well unless all surface oxides are removed).

[ReloaderFred]

It's possible to bond cores to jackets without the use of flux, but it involves high temperatures and a "soaking" period. These cores have been melted into the jackets at 1,125 Degrees F, and soaked over night while the kiln cooled down. The only way to separate the core from the jacket is to melt it.



Hope this helps.

Fred

[ReloaderFred]

Here's the old ceramics kiln I use for this job:



Hope this helps.

Fred