Molds with special requirements

Posts: 1
Joined: Sat Jun 23, 2012 9:13 am

Molds with special requirements

Post by Dick » Sat Jun 23, 2012 9:30 am

I am a commercial caster serving a small but very quality demanding bunch of customers. Right now I am using a Mountain Mold belonging to a customer. It is stamped MM279-85. It casts a 270 Cal bullet of 280 dia as cast x 90 grains in 6% antimonial alloy. My customers shoot it in the 270 Rensing single shot pistol. The mold is beautifully made, functions flawlessly, and casts equally beautiful bullets. That's just by way of background. I have two questions :

1. With this mould I cast 300 bullets per hour over long sessions of several hours. Your XL block will easily accept three cavities. That would increase my output to 450 per hour. That's important in commercial casting. Yes, I know you have said no four cavity, and I can understand that because your XL block is not long enough. But it is plenty long enough for three. Will you do it ?

2. I have encountered huge problems with 44 Mag mass produced moulds, RCBS etc. They overheat even at alloy temp of only 600, because the web of metal between the cavities is too thin. The frosting at that side of the bullet is so excessive that it doesn't fill out. The answer is a single cavity mold, which means painfully slow casting. Or a double cavity mould with the cavities spaced 25 or 30mm apart, centre to centre. Your XL block will do that easily. Will you do it ?

Dick Boothroyd

South Africa

User avatar
Site Admin
Posts: 1640
Joined: Fri Feb 01, 2008 5:45 pm
Location: Where the Salmon joins the Snake

Re: Molds with special requirements

Post by mtngun » Sat Jun 23, 2012 12:19 pm

A 3 cavity XL block is available in the online design program.

Cavities are 0.77" apart on the 2-cavity XL. They cast well at 350 - 500 grains wheelweight, and can handle up to 700 gr. wheelweight, though at that size they have to cool between pours.

You don't state which alloy you are using for your 44 bullets, but the medium-hard alloys like 3-6-91 are very prone to heat shrink on heavy bullets. You have to let the mold cool between pours -- cool enough to avoid frosting, yet warm enough to fill out, and there isn't much middle ground -- which is why I no longer make big bore molds for 3-6-91. Wheelweight is the way to go.

Post Reply