This is just some anecdotal hearsay that I remember from back in the day.
In the 1970's I was a young man riding motocross bikes and my first CZ looked like this:
Back then the bikes were too heavy mainly due to mild steel tubing frames. The talk in the related magazines of the time (1972) was the reason CZ wasn't using the much more desirable Chrome Moly steel, which would result in lighter stronger frames, was because the alloy steel was being used exclusively for weapons production.
I don't know, Chrome Moly steel can be very hard, very durable and easily machinable. Back then, 50 years ago, it was an expensive premium grade of steel.
Today it is commonly used in gun barrels.
Czech firearms have always been known to be well-made high-quality products using high quality steel.
So, I wouldn't be surprised that the early CZ75s were made out of premium material.
