[HiBC]

As a milsurp mauser is sometimes made up of mismatched parts,I have run across a situation where the safety locking lug of the bolt was bearing,and the two main locking lugs were not.One of many possibilities.

The part about the bbl apparently stretching,as "The Chamber was out of round" and "Small pieces of bolt missing"

Unless I mis-interpet that,it indicates higher than normal pressure,even for a 300 win mag,or any cartridge.As the OP still has his eyes,fingers,and apparently does not have a bolt protruding from his head,the action strength is not a problem.

So,how many ways do we get an overpressure event?

Our OP says factory load.If true,it is either a serious ammo recall,or the ammo was a normal,safe factory round and there is another problem.

The ammo mfgr has the ammo.We should get feedback,simple yes/no.

If the ammo is not,as told,factory ammo,even if it was sold as factory ammo,then there is a whole series of questions.

For good,factory ammo to result in gun damage,something had to run the pressure up.Generally,it would be some bore obstruction category.

I see bad factory ammo,bad handload,or,whether rust,mud,patchgrease,whatever,something obstructed the bullet.

Or,maybe,our maligned original gunsmith appraised a level of workmanship he found substandard,and maybe "go use it for a tomato stake" was that colorful,succinct gunsmith way of speaking.Too many unknowns!