I just lost the whole damm reply !!!

Here goes again.

I think that 10b will do you a favour as it will force the barrel profile and give more mass between the hands. If anything you may have tribulations making this heavy enough for caliber.
Barrel makers can usually calculate the finished weight of barrels for any given profile.

Are you going to re-stock? as the straight hand may give you issues of control in .600 and bruised middle finger. it may also snap the stock across the hand

Metalergy.

The co. whos link you posted could proberbly advise you about x-ray or magnafluxing to be sure of the action for cracks. A good precaution.

It will be low carbon case hardened steel. Hardness can be tested.
I would stear clear of the co.s that offer bone and charcol colour hardening. most I have seen are less than scientific. OK for a 71 winchester with pistol cartridges, not so great with the ammount of energy involved here.
Again you have found a good company there as they also do hardening and can assist you with this I would imagine.

I would as I posted before regulate for the lighter standard loading.
Larger cal lower pressure may apply, but the thrust is the factor and thet is proportional to case head diamiter for any given pressure. I have an old listing for the 1850 fps load that rates it at 11 tons which is very low by NE averages for the smaller calibers.

I still think that you need to bush the firing pins. I would not make removable discs as it will not see that ammount of use. But simple bushes to reduce diamiter. You can then cut off the striker nose, drill in and braze a piece of A2 and reshape for correct protrusion

Regards.

And if this bloody thing crashes again you will have to phone me !!!