I shoot the original cetme serveral times when I was overseas.
In full auto bursts is hard to control like the FAL. In single shot is a joy to shoot.
It is heavy and stout but it is a good way to tame the round. Fairly accurate too.
Keep in mind these are not piston systems and opens with the case thrust using the roller delay block.
The brass stretches more than other rifles and the chambers are fluted to help with the extraction
so if you reload consider this. This is no different than other delayed blow back.
These were model D that were maintained by expert Spanish Marines Armorers and had excellent
triggers and parts. I also shot the 5.56 model L that was light and utterly reliable like the 7.62.
The Spanish did a great job with these rifles that were in service for generations.
It ran smoother than the H&K, felt more robust and I am sure the expert maintenance had a lot to do a lot with it.
Not sure about aftermarket or Century. With Century and other rifles like the AKs I have seen it can
be a hit or miss situation like canted sights, crappy triggers, chamber issues, etc... but others
get a decent retrofit. Like anything the QC needs to be there.
There might be other brand that retrofit that follow all the specs and inspection points but not sure who.