If you're left without a replacement barrel and are facing the prospect of a custom made barrel, I can recommend IGB-Austria.
IGB Austria / Online Shop

They make very high end barrels.
Check out this very exotic job they recently did on a very nice Hämmerli P240:
TargetTalk • View topic - Bulged barrel of my SIG H"ammerli P 240
There's some good links along the way through the thread.

Anyhow, IGB is enthusiastic about taking on custom work for one-off guns.

Best Regards,
Jim