Back in the early 90's a buddy re-barreled a Spanish 93 to .308 Winchester. All went well until one day he was shooting up a batch of European NATO 7.62 surplus ammo, and he experienced a pierced primer. The gases that spit back in his face could've blinded him had he not been wearing safety glasses. Points to the fact that M93's had poor gas handling characteristics compared to later Mauser designs and most subsequent commercial designs.
I often read of that in journals and around the internet, and always have to agree, based on admittedly a sample of one personal experience. Still and all...
IMO, the pre-1898 style SR Mauser actions biggest design fault is the way that it channels escaping gas from a pierced primer or separated case back toward the shooter. That is why when I build a rifle on a Swedish military or Husqvarna commercial SR pre-1898 style Mauser action, I install a commercial style bolt shroud from Brownells with a larger gas shield.
This isn't my project and I've said my bit, so que sera sera.
