Drill Out For Paper Patched

[Good Cheer]

Any of you guys tried drilling out molds to make smooth sided castings for paper patched, in cartridges or for muzzleloaders?
How did it work out?

[beshears]

Drill bits do not cut round or smooth enough for a bullet mold, you won't find the correct size also.

[longbow]

If you want a simple to make mould for smooth paper patch boolits, copy the old Ideal Cylindrical mould design:

http://castpics.net/wp/wp-content/uploads/2020/08/IDEAL-BULLET-MOULDS_-THE-BARLOW-AND-MARLIN-YEARS-1884-1915.pdf

Scroll down to figure 11.

Here's a graphic:

288312

I have been making these for about 50 years on and off with excellent results. I have used the idea for shotgun slug moulds, .44 mag. moulds and .30 cal. moulds for my .303 British. I use 1 1/2" round bar though and a conventional sprue plate.

They can be made in any diameter you want by simply boring the cavity or making a D-bit, rough drilling then use the D-bit to ream to final diameter. I have used them for paper patch boolits as cast with smooth sides for .44 mag. and .303 British tumble lubed and also from moulds made somewhat undersize then boolits knurled to groove diameter+ and tumble lubed. I also cast Foster and Brenneke style 12 ga. shotgun slugs in cylindrical moulds. I call them push out moulds because I use the nose form/HP/HB pin as an ejector to push the cast boolit/slug out of the mould.

Moulds can also be made in HP and HB.

I have used mostly cold rolled steel bar fore mine but have also used stainless steel, hot rolled steel and bronze. All work fine except stainless steel is a poor conductor of heat.

You do need a small lathe to make one though.

The 1st push out mould I made was a wadcutter HB mould for my 20 ga. shotgun back in the 1970's using just a drill press and yes, a drill bit. I had to lap to final diameter to get a smooth cavity because of what beshears points out... drill bits do not make clean holes! I would no use a drill bit for a split mould. I doubt it would stay centered.

Food for thought.

Longbow

[Good Cheer]

Remember the Ideal adjustable length core molds?
The .44 core mold produces a .392 boolit that's perfect for a .40 bore muzzleloader.

[Good Cheer]

I used a 3/8" drill on a set of Lee blocks in about 1975 or 6.
It worked well.

[country gent]

What I would is to do it like this.
Clean blocks well of dust oil and other debris,maybe even lightly etch then.
Cut a thin piece of tracing paper to match outside of blocks and clamp inside. this gives a small gap of soft material for the bit to follow. It also aides in keeping chips from loading up.
With a drill .100 smaller drill close to depth.
finish drill with a drill .005-.010 under desired size
but a finish reamer .001-.002 under finish size and ream.
cast some slugs and see what you have then lapp to finish size.

Hold the blocks in a vise or clamped to the machine and align them with an indicator. Cut slow and use lots of oil. Clear chips often.

The big obstacle is unless you can make a d bit o form tool is going to be getting the nose shape you want formed

[Nobade]

Bullets are too big to start with. Need to be bore diameter +.001 for smokeless, and under bore diameter minus the patch for black. Better to get a dedicated mould, or make one as above.