[AMX]

Rubbish.
1) Autofrettage was developed in the 1920ies; while it's possible that Rheinmetall holds the patent for the best currently available method, assuming that others can't use it at all is nonsense.
2) All the more so as GDLS would likely have licensed said method along with the gun.
3) The weights in the article are off - their "best case" weight (2.7 tons) is far higher than the actual weight (1315 kg tube only; even with breechblock it's less than 2 tons).