Boltface/ bolt head custom cut

[1911man]

I am looking into the possibility to change a bolt face, bolt head from an sig cross to a 6.5 / 6 arc. What will be involved? Would it be possible? MDT mags, new barrel with use of factory, existing, barrel extension.

[sigstroker]

I am looking into the possibility to change a bolt face, bolt head from an sig cross to a 6.5 / 6 arc. What will be involved? Would it be possible? MDT mags, new barrel with use of factory, existing, barrel extension.

It would be a lot easier and cheaper to rebarrel it into a 6 Creedmoor. Or 6 Gay Tiger or other 6's. Then you wouldn't have to change the bolt head at all, just the barrel.

[ar15barrels]

According to this page, I only see 0.473" case head chamberings so I suspect there are only 0.473" bolts available.
If you wait a while, maybe they will introduce a 0.38" or 0.44" bolt that would be more appropriate to your conversion.
Otherwise, you are going to need to soft solder a sleeve into the boltface and custom make an extractor to get reliable function of smaller cartridges in a 0.473" bolt.

It seems like a lot of work just to make the rifle have less performance.
It would be easier to load lighter ammo in 6cm or 6.5cm.