increase a bullet mould diameter?

polaris

polaris

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Hi,
any info how to increase the diameter of a RCBS 44cal mould?
are there companies specialized in doing so?
or can i do it myself?
Thanks
 
Depends on how much. The cooler the mold the larger the bullet, and some alloys such as the linotype drop at greater diameters, but only +/- 1-2 thou at most. Some success is possible with placing strips of aluminum tape between the mold halves ("Beagling"), but the dropped bullet is slightly oblong, coming back mostly to round upon sizing, and the rest of the way upon firing.
 
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Andy said:
Depends on how much. The cooler the mold the larger the bullet, and some alloys such as the linotype drop at greater diameters, but only +/- 1-2 thou at most. Some success is possible with placing strips of aluminum tape between the mold halves ("Beagling"), but the dropped bullet is slightly oblong, coming back mostly to round upon sizing, and the rest of the way upon firing.
Click to expand...

thanks, saw this method on you tube, might be the easiest way to go.
where can i find that tape? home depot?
 
Another thing you might think about is powder coating the cast bullet. This can increase the diam. by 1-2 thou. In addition, you could then size down the PC bullet if too large.
 
polaris said:
thanks, saw this method on you tube, might be the easiest way to go.
where can i find that tape? home depot?
Click to expand...

Yes, in probably any hardware store - it's used to seal joints on ducting.

just having some fun said:
you can lap a mold with valve grinding compound
Click to expand...

I've done that with some success, but it's of course not reversible, best done with aluminum molds (read Lee) and can produce a less than perfectly smooth surface (mostly cosmetic however).

I did it with a Lee two cavity on only one of the cavities. I got the mold very hot and the alloy as well to give me more time. Have a drill bit secured in a small "vise grip" plier nearby. The next part takes practice and took me five tries before I got it right. Fill the mold (with a small puddle of a sprue), and rest it on a flat surface, quickly place the spiral end of the drill bit into the molten alloy in the mold and hold until the alloy solidifies (we're talking 2-3 seconds!). Try to have the drill bit centred and square to the bullet. It doesn't have to be perfect, but if it's off by much, the next step won't work. After everything cools, chuck the drill bit with cast bullet attached into a hand drill. Coat the inside of the mold generously with grinding compound, starting with coarse. Insert the bullet into the mold and close the handles. Rotate it within the mold slowly until the valve compound is exhausted. Repeat 3-5 times with coarse, then clean and have a go one last time with fine. Clean thoroughly and try it. In my case, that added 3 thou to the diameter of a mold that previously dropped at 0.430".

This is very much trial and error and is irreversible, ergo using a Lee Mold.

This video illustrates it. It's not me, but it's the same mold I used!

 
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If you have to pay to have the work done I suspect that you could order a custom mold from Boomer's Bullet Moulds, as cheaply.
So much depends on what you actually want to accomplish, and your own shop capability.
 
I use aluminum muffler tape to "Beagle" my molds. I have gone as much as one thickness per side in one of my molds, and any more thickness I start to get finning and oval boolits. It's finnicky stuff to work with, and I have to cut very thin strips to fit the mold, but don't have to worry about getting right next to the cavity. So long as the tape is sticking to the mold, and it's on both sides of the cavities, then I can usually get a good fillout. I have only done double cavity molds, and haven't had the need to try it on a single cavity, and I don't have anything more than double cavity molds.

A single strip will add about .001 to .0015. Two strips about double that.

I bought a roll of aluminum tape at Crappy Tire. I can't remember if it was flashing tape, or muffler tape. A small roll will last a couple of lifetimes, but at least it's cheap!
 
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I've tried the beagling and lapping on a few of my molds, mostly aluminum with limited success.
The one suggestion already mentioned is to powder coat then size to your desired thickness.
There's an initial cost but I have to admit it was one of the smallest investments I've ever made into the reloading hobby.
~$20.00 for a pound of your favorite PC colour and the same for a used yard sale toaster oven....and the added bonus of not modifying and potentially pooching your factory mold.
 
I've got a buddy that modified a Lee mold so he could shoot 220 gr cast out of his .303 Jungle Carbine, he'll probably chime in soon if he sees this thread.

I think he just drilled it deeper on a press, lapping compound to smooth it out and that was pretty well it.
 
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