Hi,
I also started my discussions with JD at SSK. But he was not able to provide CIP proofing. He explained me, that once during proof firing for european CIP proofing a gun broke.
Then I found a gunsmith here and he was able to make my dream comes true.
He installed a new barrel made out of the best steel "Böhler Super Rasant" which is strong enough for the relativly thin chamberwall where the threat is.
To gain some weight the barrel is nearly cylindrical, has Magnaport and also some lead in the stock. The gun´s weight is about 10 lbs.
He needed to cut some material from the system to slide the cartridge in the chamber. But as the weapon is tested with 30% overpressure it´s save.
Check photos....(The other cartridge is 30-06)

Tom