Core bonding

[WIB3]

Has anyone been able to get results from bonding cores to jackets using an induction system. I have success over the years bonding cores with an other method. Wondering if anyone has perfected the induction method yet.

 

[Dusty Stevens]

Can you actually weld lead to copper? Having the core properly swaged into the jacket is one of the most important aspects of a good bullet. If you melt that core the bullet is ruined. Bonded cores are mechanically locked not melted to the jacket

 

[wboggs]

Can you actually weld lead to copper? Having the core properly swaged into the jacket is one of the most important aspects of a good bullet. If you melt that core the bullet is ruined. Bonded cores are mechanically locked not melted to the jacket

Many years ago I tested bullets for Bill Steigers of Biterroot bonded bullets using a .378 wby. We found the core and jacket stayed bonded together giving a large frontal area but reduced penetration. They were suboptimal on Alaskan game.
The lesson is that you must match your bullet choice to your use. It makes no difference in deer and smaller game but is all important in large or dangerous animals.
Just my opinion.
Bill

 

[dcali]

I’m curious - how do you define success? For swaged bullets, the core is pretty well stuck to the jacket, at least at room temperature and zero rpm.

what’s the goal? Terminal ballistics?

 

[wboggs]

I’m curious - how do you define success? For swaged bullets, the core is pretty well stuck to the jacket, at least at room temperature and zero rpm.

what’s the goal? Terminal ballistics?

I assume bonded bullets are used for hunting. Terminal performance on game is the goal. It is not always equal to a well mushroomed bullet that has the jacket and core intact and looks good. Penetration and the ability to destroy tissue from difference shot angles produces superior results on large game. Deer sized animals do not demand much in the way of bullet performance and design is not that important. Move up to elk and larger and it is a different story.

 

[PDS]

Here's a video of a production setup.
https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=13&cad=rja&uact=8&ved=2ahUKEwj-9JWZwMTlAhUJlKwKHaKJDAUQtwIwDHoECAwQAQ&url=https://www.youtube.com/watch?v=Iq98FC9HMqM&usg=AOvVaw1dPrR3plCnalAOvsUqne4N

 

[WIB3]

Not to disclose too much information, but if familiar with the swaging process the lead core is pushed up into the ogive in the die. Most assume that it is equal on all sides. Many factors can and do affect this uniformity. By melting the lead core after forming on a perfectly flat surface, on can eliminate this variable. When fired the bullet spins at an extremely high RPM. Bonding the bullet core has other benefits other than hunting when done properly.

 

[WIB3]

I did this years ago with 250gr Sierra MK’s. The problem than was Sierra made these with 240 jackets. They would blow up when pushed to hard. It solved the problem.

 

[David101]

Lead should bond to the jacket when melted, I assume anyway. It may require flux or perhaps a pre treated jacket. I would think it is a bit like a lead/tin solder.

 

[WIB3]

The process requires that only the ogive of the bullet receives heat. If the shank of the jackets get to hot it will soften the jackets and fouling and failures occur. That leads back to my post if anyone with current technology is using induction. It would be far mor precise.

 

[WIB3]

I’m curious - how do you define success? For swaged bullets, the core is pretty well stuck to the jacket, at least at room temperature and zero rpm.

what’s the goal? Terminal ballistics?

 

[WIB3]

No, bullet stability.

 

[dcali]

Not to disclose too much information, but if familiar with the swaging process the lead core is pushed up into the ogive in the die. Most assume that it is equal on all sides. Many factors can and do affect this uniformity. By melting the lead core after forming on a perfectly flat surface, on can eliminate this variable. When fired the bullet spins at an extremely high RPM. Bonding the bullet core has other benefits other than hunting when done properly.

Sounds like a lot of work. Do you flux the jackets/cores before forming?

 

[RGRobinett]

Nice video of bonding cores (thank you PDS) - similar to, but much faster than the "hillbilly" method I employed almost a decade ago, when working on a bonded-core precision bullet, for Greg Sweezey (Gold Creek Rifles) and one of his customers.

The goal was to make a bonded-core match quality bullet, which could be substituted for BIB 187 Gr. FB bullets, delivering the same point of impact, and equal group size ("cheaper tuning &practice). Both objectives were achieved. The bonded bullets and the non-bonded variety could be interchanged without concern of either zero shift, or, precision decay. The BIB 187 FB Match were an exceptional bullet, having won IBS and NBRSA 1000 Yd. bench-rest tournaments, including National Championships, and a ten-shot record, by Joel Pendergraft, which held off the VLD type bullet for just over a decade. So, the [FB] quest was worthy . . . and remains so today.

The process was just too slow, and, after a fair amount of testing, the bonded bullets, on moose sized animals, usually did not produce the 100% penetration - exit - which the end customer desired: the majority would be captured by the off-side hide. Further, the retained weight ran about 70-75%, while though he wanted exits, for the bullets failing to exit, the customer desired 100% weight retention: these objectives proved unobtainable. That said, from near range shots of 30- 50 yards, out to 1,100 yards, the experimental BIB .30 Cal, 187 GR. Bonded FB proved deadly.

Yes, quite excellent bonded-core jacketed bullets can be made. As wboggs stated, above, I would not shoot them at something which might bite me!RG


Joel's 10-shot (HG) record group - BIB 187 Gr. FB.


During the quest above, another weird attempt at slowing/stopping expansion was to insert a stainless steel ball-bearing (sans the "bonding") just above the [axial] mid-point: this produced the opposite effect! Dugh - what was supposed to hold the jacket walls together?!!?
Counter-intuitively, the ball-bearing bullets shot GREAT (groups), but the expansion was violent, and penetration limited.
At longer ranges - beyond 400 Yd. or so, the 'plain Jane' non-bonded bullets proved much more deadly than the bonded core version - the latter were better inside that range. The cartridge(s) were big: 30/378, .300 Ultra Mag., other .404Jeffery based wildcats, and the like.

 

[WIB3]

Sounds like a lot of work. Do you flux the jackets/cores before forming?

Hydrogen gas is used as a flux. The process must be performed in a oxygen free atmosphere. There is no oxidation on the surface of the copper. It’s an industrial process that has been used for many years. Unfortunately hydrogen is extremely dangerous and the process can not be performed in one’s basement.

 

[WIB3]

The process is performed on a finished product. I don’t manufacture Bullets. Just try to make them fly better.