Whos' made one? Old style PP Mold

[Jim Flinchbaugh]

I might try this, any one been there done that?
Primary question is what kind of clearance between the nose cup and the main body so you don't get a mold line, but it will still eject the boolit when it gets up to temp?
http://img.photobucket.com/albums/v313/James64/Brennan4-4HOWTOMAKEAPAPERPATCHEDMOLD-9.jpg

[I'll Make Mine]

As long as the nose cup and body are the same material, they'll expand at the same rate, so the fit can be a "close sliding fit" -- which, to a machinist, means .001" to .004" clearance. Molten lead running into the gap shouldn't be a problem, but even if you can keep the fit at the close end of that tolerance, you're going to have a visible ring where the cup ends. Shouldn't matter, you'll be wrapping the patch over it anyway. Alternately, you could leave a little bit of a flat on the rear end of the cup, and get an "ogive semi-wadcutter" sort of tip that will cut paper cleanly with little effect on ballistics (the cutting shoulder would be inside the shock cone at any velocity above transonic).

You might be able to get a reliable sliding fit with much less than .001" clearance, but it'll require reaming the cavity in the body (to get acceptable smoothness and accuracy) and lapping the nose cup to fit (for each nose cup, if you want to cast different nose shapes in the same mold).

[longbow]

I have made several moulds like that and they work quite well.

I use 1 1/2" round bar for mine as it leaves enough diameter to make up to 12 ga. slugs and still have a swinging sprue plate.

I would argue that anything over about 0.001" clearance for the sliding nose form is too much. I make mine to "just fit" by turning the nose form and then using emery cloth to polish it down until it will just barely slide in.

So far I have made:

- PP mould for .308 WIn using an "N" reamer which cut the cavity at 0.302" so cast boolits are 0.301" which is perfect for standard .30 cal
- 0.421" for PP in my .44 Marlin
- 0.434" smooth for use over a lube cookie in my .44 Marlin (shot much better than the undersize Lyman 429421 I had at the time
- 12 ga. full bore slug mould
- 12 ga. wad slug mould
- several at 0.305" + nose and 0.313" to 0.318" body for my .303's

I am currently making an undersize mould at 0.310" to suit knurling up to 0.315" for my .303's.

I have made them similar to your graphic with full diameter sliding nose form in one and two diameter (nose/bore rider design) and also my machining high carbon steel to the boolit shape I want then making a D bit by milling it to the center line then heat treating. The D bit is used like a reamer to make a finished cavity. I use a small ejector pin at the nose to push out the boolit after casting.

All work well.

If you plan on a PP mould (for smokeless powder at least), you might want to make it slightly undersize so you can knurl the boolits by rolling under a file to give the paper some grip. I haven't found it a problem with large bore but my .303 seems to like a "rough" boolit. You can always lap it larger later if you want anyway.

Some here (pdawg shooter for one) recommend using regular cast boolits sized to PP diameter because the lube grooves help keep the paper patch from sliding. Knurling has the same effect.

I make them because I can and I can make any diameter I want to suit my odd size bores.

Longbow

[Jim Flinchbaugh]

I was trying to decipher a way to add the "knurling" you mentioned, the file is a great idea! Thanks!!!!!!!!!

I have a Sunnen pin hone and access to mandrels- I can hold tolerances to the .0001" easy :mrgreen:

[Jim Flinchbaugh]

make it slightly undersize so you can knurl the boolits by rolling under a file to give the paper some grip.

Longbow

Any particular pattern or cut to the file for a preferred "knurling" pattern?

Any photos? How much smaller- I assume you can change the increased diameter some by the pressure applied by the file while rolling?

[pdawg_shooter]

Any particular pattern or cut to the file for a preferred "knurling" pattern?

Any photos? How much smaller- I assume you can change the increased diameter some by the pressure applied by the file while rolling?

I used a sharp (new) mill bastard file when I fought with "slicks". I have gotten rid of all my PP molds and now just size standard grooved bullets for patching. The grooves hold the paper in place and hold a bit more lube.

[Jim Flinchbaugh]

I messed around with some in the shop today, I can easily add .003-.006 depending on the cut and pressure applied

[Nobade]

I made one of those moulds out of 416 stainless (old chunk of barrel) - don't do that. Stainless makes a poor mould. By the time it gets hot enough to start making good boolits the ejection pin starts to gall and it all goes bad in a hurry. I think the next one I do will either be cast iron or brass.

[longbow]

The first "knurler" I made was actually a "groover". I had read on the Corbin Site (I think) that you just can't knurl hard lead so I decided that if I made a grooved roller I would be able to roll annular grooves (I call them microgrooves) into the surface regardless of hardness. Depth might be affected but I should get grooves.

Well, with ACWW they grooved easily and quite nicely expanding diameter by about 0.003".

This seemed about perfect to raise the as cast diameter from 0.301" to nearer bore size and roughen up the surface of the boolit.

That made my .303 much happier shooting PP boolits.

The only real problem was that the grooved roller would occasionally slip ruining a boolit.

Since I was also using this for GG boolits. I made some changes that weren't conducive to paper patching but I won't go into it here since this is for paper patching.

The final result now is a knurled and grooved boolit with diameter increase of from 0.005" to about 0.010" larger depending on pressure used ~ it needs a positive stop added to set diameter.

I have knurled some 0.301" boolits to 0.308" for PP'ing with tracing paper for my .303 but have not shot those yet.

Using a file will take a bit of feel to set "knurl" depth and so boolit diameter consistently. You might try using a set weight on the file ~ a physical weight, or maybe spring scale to keep consistency.

I thought about a jig to hold the file a set height from a steel bar to make consistent knurling too but since I made a knurler I didn't bother. It should work though.

You shouldn't need a lot of knurl depth to grip the paper I wouldn't think.

I had a bunch of photos posted but removed most or all because I used up too much space. I should set up a Photobucket account or something.

If you want a few photos of a D bit, mould and/or knurler and knurled boolits I can repost or e-mail them to you. I should have some handy.

Oh, the Corbin site still has knurlers and I am not seeing any warnings that you can't knurl hard lead. I certainly have no trouble with mine on ACWW. If I want harder I can oven heat treat after. For paper patching it shouldn't matter, ACWW should be fine.

Yeah, stainless is a poor mould material. I didn't have any trouble with galling but stainless is a poor conductor of heat so tends to overheat quickly. I have a 12 ga; slug mould made of SS. Not a good choice!

Plain old mild carbon steel works fine and bronze is really nice. I had actually asked the shop for brass so they cut a dirty bar and sold it to me but it turned out to be bronze. Made a great mould though!

Aluminum should also make a good push out mould but I have not tried it because no-one local had 1 1/2" aluminum round bar. Aluminum would be easy to machine and easy on D bits.

Long post! Sorry, I am rambling.

Longbow

[Buckshot]

............If you make it out of aluminum you might not have to 'eject' them :-)

http://www.fototime.com/025DBFFE3B48D69/standard.jpg

This was my first attempt at making a core mold, and made a few mistakes. But I suppose those are immaterial since the thing works. The second one I made without any hiccups LOOKS better, but works no better :shock: Anyway, my point for posting is that I don't even have to open the blocks to get the cores out. Simply swing the SP to cut the sprue, turn the mould upside down and usually all 3 cores simply fall out. Occasionally one will come out half way, but a light tap and it falls right out.

I cannot see why one bored out of a single block wouldn't work as well, especially with the softer alloy you'd no doubt be using? The softer the alloy the more it shrinks. It would also eliminate the need for alignment pins and their mating holes, handle slots and screws also.

................Buckshot