41 Luby, one of my favorite K98ks.
The Spanish Guardia were not 308 but 308 CETME which is a very light load.
You likely know this but just being careful just in case you don't.
A 308 round is way too powerful for the small ring Mauser (60,000 PSI on the higher loads) and even the NATO 7.62X51 which is 50,000 PSI is too high for this 93 Mauser cation
The Spanish used a specific light load for these as trainers as well as police etc guns.
However, I am not aware of any of these blowing up to date but i would be cautious about anything in 308 and stick to 7.62X51 NATO rounds or even better load it lighter than the NATO rounds if you reload. Check your head space on these even with NATO loads to be safe.
Welcome, there are people like me who know a little here and there are some heavy hitters who are the reason why many of us come here to pick their brains.
I have had a couple of these in both 7 and 7.62 so was relaying experience and researched info
Wulfmann