Been reading this thread off and on, and most of the posts.

My only "experience" as a user of a shotgun conversion was having a few shots through Marrakai's "Fat Lady" .577 on an Greener Empire 12 gauge shotgun action. Now owned by another member "264".

I would have been happy to own that .577 Double rifle shotgun conversion myself.

The gunsmith converting this shotgun was Rolf then at London Guns in Melbourne. I spoke to Rolf about it and getting him to make one for me, and he said "No Way!". The risk and liability to himself was no longer worth it. And he also claimed, the cost would be similar to buying a ready made double rifle anyway. Perhaps the latter was not true, as a .577 DR is rarely cheap, unless BP only. But he made the .577 DR and a .577/12 g cape gun. But would no longer do it.

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I can see the pros and cons of the arguments above. For a gunsmith doing it, they will need to accept and understand the risk. For any owner selling one, they also need to understand the liability to themselves as well.

Luckily Australia is less litigious than the USA. And also if a gun does "explode" other risk factors may also be affecting the incident, eg a dirt plug in the muzzles of the barrels, incompetent relaoding techniques and loads, and other factors.

There are reasons firearms made in non mass produced factories cost more, and more than parts of simple labour. Quality control and liability and risk control are also part of it.