HobbsPal, one thing you should do is ensure that the mould blocks are properly closed.  All that you need to do is close the blocks ( using the mould handles and your standard amount of grip ) and look into the cavity while holding the mould up to a strong light source.  You should not see any light coming into the mould.

It may seem obvious but if the blocks are not closed properly you can easily add a thousands out of round.  This is sometimes caused by a fleck of lead preventing complete closing of the mould.

If you are like me then you'll eventually own many moulds.  A cheap one is the best way to learn to get started.  Especially if you follow the advice given in some publications that involves cutting sprues and dropping sticking bullets by rapping on things with a piece of wood.  You'll learn that good leather gloves will enable you to cut the sprue by hand and that proper mould temperature and even cadence prevents bullets that stick hard in the cavity.

Should that 0.003" out o round really bother you then a nice compromise is a Buffalo Arms mould. Not quite custom, but they are very high quality. I own several and all are very round. 

Chris.

[quote author=626F7E676B7C7C6B3F0E0 link=1369590550/14#14 date=1369742529

... straight wheelweights work well for me with lots of different styles and weights of bullets.  got a never ending supply of wheelweights so that helped influence me in that direction.  nothing like getting out and casting and shooting what you've cast to show you what you're doing, or not doing, correctly.  some people don't like the casting aspect of shooting but i do.  don't get in a rush and pay attention to what you are doing.  one of the nice things about casting lead is that if you make a mistake you can always re-melt it and do something different.  it is a fun hobby.           [/quote]

When I use wheelweights I use 1:10  ::  wheelweight:lead: that makes it plenty hard enough. (No local tin supplier)

I have made bullets that jingle when shaken in a bag by adding auto diecast metal as a hardener, but I don't reccomend it for anything other than armour-piercing stuff fired in a sabot...

Aonghas