Daryl & OG:
I acquired a Ross M-10 in .303 many years ago for the sole purpose of testing the "bolt mis-assembly" theory for myself. The rifle was a deactivated DP example and I picked it up for beer money. Well worth it for the first-hand lesson.

The bolt can indeed be assembled and fitted to the action in such a way as to fire the cartridge without the locking lugs (threads?) being engaged. I can only assume that the results of firing it in that condition are not exaggerated in the literature!

Granted, the mis-assembler would have to be a little dense to do this and not notice, but it is certainly possible, and not difficult!

My understanding is that a vertical pin through the bolt body was a retro-fit that worked, but by the time that was conceived the M-10 had proven itself short in Canadian service on the Western Front and was replaced by the Lee Enfield.

In the sporting field however, these limitations need never arise and as I understand it the reputation of the .280 Sporter was untarnished.

Apologies for the minor thread hijack, I do incline to ramble sometimes...