I have a Corbin brand bullet swaging tool. It is pretty much like a very large reloading press that grew to twice its size, and became squared and true to 0.001"
I could make 160 grain round nose bullets at .264, .266 and .268 diameter (there is a lot of variation in bore sizes).
I also have a custom cannelure maker. There is an excellent hand model available from: http://www.ch4d.com/
I would go ahead and bond the jackets to the cores. With the bonding the bullet should hold together pretty well.
I had the devil's own time trying to get my original carbine to shoot anywhere near straight.
Does any one have a picture of some original cartridges? That would be a lot of help.
The Lapua nose is not quite a round nose. It looks a lot like the old Hornady .375" 270 grain "round" nosed bullet. I will order some of those up this week, along with the correct brass.
When I get the operation up and running I will ask customers to have their gunsmith slug the barrel for inside diameter. I will also offer a "try pack" so they can see how the different bullet shapes do in their particular carbine.
Hornady does make a .2675" round nosed bullet withoout a cannelure. That was designed for the Carcano. Hornady sells Carcano ammunition as a house brand through Graf & Sons, a mail order wholesale/retail outlet in Missouri. They may ship to Oz. It is certainly worth an E-mail.