Building a core mold

[Crawdaddy]

I bought 6 feet of aluminum stock last night for the purpose of building a core mold. (yikes! 10 bucks a foot!)

This will be my first one.

I am seeking input on a couple of items

44 magnum made from 40 S&W cases

What size drill but should be used?
What size reamer to finish it?


458 and 450 Marlin from 44 mag cases
What size drill but should be used?
What size reamer to finish it?


Any other advice you can add?

[Reload3006]

I use .340 lead wire and my core swage die makes slugs .375

[alfloyd]

The bottom of the 40 S&W brass rounds to about .340 dia at the bottom. Therefore the core for them should not be greater than the flat bottom or you run the chance of trapping air in the bottom. If you deprime the case to make slugs with them this is a mute problem. If the primmer is still in the case then it needs to be addressed.

Just my thoughts on the subject.

Lafaun

[MightyThor]

On my 22 bullets I load cores in a shaker system that loads 100 at a time. The cores have to be sized so that they drop into the jacket. I have pictures on the 22 cal sticky. If you are going to hand load the cores you can make them a little more snug.

[Reload3006]

if trapped air is a worry for you deprime the cases. Some day you may want to use regular copper jackets either made from copper tubing or some you find to buy. Gilding metal jackets are by far the best not the cheapest by any means but better bullets. But the best advice is to make the core mold as small as is practical because you can squeeze the lead to make it bigger but its pretty tough to squeeze it to make it smaller.

[DukeInFlorida]

I use .40 FN cast boolits as cores, upside down in the case, in the .40 cases (I run an expander into the cases to open the case mouth, and then push them solidly in) for the 44 mags. Obviously, the meplat is smaller than the diameter, so it works out great. I use a Lee tumble lube cast bullet mold for making those cores, and they never fail. Not sure I would even try to make a core mold for that caliber, since it's just as easy to make the Lee version cores.

Going with straight walled cores would require that the diameter be something less than .400

[Buckshot]

................I wouldn't depend on a reamed finish to get you where you want to go. Instead I'd suggest boring to get the finish that would be best. I don't know what kind of equipment or tooling you have, or available to you so I'll just show what I did.

http://www.fototime.com/5F9B1C52B08A8C1/standard.jpghttp://www.fototime.com/A0D59ED4A51A13D/standard.jpghttp://www.fototime.com/11609D54AA9989C/standard.jpg

LEFT PHOTO: Not a core mould, but a mould for casting 'proof slugs', but the cavities in a slug mould can be done the same. CENTER PHOTO: After the majority of the aluminum was removed by drilling, the cavities were created using a boring head and a home ground form tool. RIGHT PHOTO: Form tool ground from a 1/4" reamer blank.

http://www.fototime.com/1E69FACFF7FA727/standard.jpghttp://www.fototime.com/025DBFFE3B48D69/standard.jpg

A 3 cavity adjuctable core mould I made using simple extruded 6061 aluminum. The blocks are 3/4 x 1.5". The sprueplate and baseplate are 1/4 x 1.5" plate. They cast cores to make slugs for paper patching for a 38-55.

http://www.fototime.com/52F297DD71E4D34/standard.jpg

A cast core and a finished slug.

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

[Crawdaddy]

great pics, thanks.

I ended up using a 25/64" bit and just drilling it out. It never occurred to me to use several bits to step it down. I have two lathes and a milling machine but I must say I am not much of a machinist.

I finished the mold last night. I will post pics this weekend. The cores end up rough but it doesnt seem to matter.

I like the adjustable aspect of yours, mine may eventually look like that. What I did was cut different size inserts to drop down the mold for different size cores. Kinda a PITA but it works.