Another way to Increase a Mold's Diameter

[Andy_P]

I need a mold that will drop a 44 cal bullet at 0.435".

I have a Lee Mold (90299 - the "Micro Band") that drops at 0.430".

I took a 7/16-14 (NC) Bottoming Tap and ran it into it.

Presto, drops bullets at 0.436". :mrgreen:

This is an old trick that works on any mold that has a Tap near in size and a bit larger.

[454PB]

Now that is hard core!

[Lumpie]

I know a person that makes his bullet lube, by mixing Rabbit droppings and Johnson paste wax? Lumpie

[copdills]

lube on the Run

[missionary5155]

I need a mold that will drop a 44 cal bullet at 0.435".

I have a Lee Mold (90299 - the "Micro Band") that drops at 0.430".

I took a 7/16-14 (NC) Bottoming Tap and ran it into it.

Presto, drops bullets at 0.436". :mrgreen:

This is an old trick that works on any mold that has a Tap near in size and a bit larger.

This is another example what makes this site so interesting... Simple solutions that work... :)

[wonderwolf]

So they drop threaded? Can we get a picture? this is a great idea :Fire:

[Andy_P]

Here's a pic. This is embarassing because the picture quality is poor, the bullet was dropped hastily to see how the concept worked, and the mold is not yet fully tapped - I used a standard taper tap, while I look for a bottoming tap that will get all the way down to the nose without bottoming out. I used a Lee Micro Band Mold because:

- it's inexpensive;
- it's easy to tap; and
- the thread is quite compatible with the microbands (makes a sort of cross-hatch pattern).

L to R - the Mold, the threaded bullet, the unthreaded bullet

http://www.pridham.ca/Threaded_Mold.jpg

The large cavity is a previous exercise where I drilled it and tapped with a 5/8" tap to make a bullet that couold be sized to 0.590" for a Snider Enfield. See http://castboolits.gunloads.com/showthread.php?t=5026

[Cap'n Morgan]

The only problem I see, is you may run into a gas blow-by problem as the helical threads will not seal the bore completely.

Another way to enlarge an aluminum mold cavity is to make a mandrel on a lathe wich mirrors the shape you want. Place the mandrel between the mold halves and give it a good squeeze in a press. Carefully remove the raised material with a fine file, and repeat the process if necessary.

[Andy_P]

The only problem I see, is you may run into a gas blow-by problem as the helical threads will not seal the bore completely.

I can't see how that would happen. The rifling interupts the raised portions and seals it off into multiple partitions.

[Cap'n Morgan]

I can't see how that would happen. The rifling interupts the raised portions and seals it off into multiple partitions.

Andy,
Just speculation on my part. :-D

As long as the outside diameter of the bullet you want to modify is larger than the distance between the lands of the bore, there's no problem. However, if the "core diameter" is smaller than the lands, the pressure will have a channel to follow all the way to the front of the bullet - unless the lube can keep the pressure at bay.

[Willbird]

Many machinists make bottoming taps from plug taps by just grinding the end off without overheating it. They work ok for most purposes even though they are not true bottom taps.

Bill