Don't buy one if you plan on reloading if flutes the cartridge.
I reload brass from HKs all the time. It does shorten brass life to about half. Mostly tho I shoot non-reloadable surplus through my CETME so I don't worry about it.
The CETME is a great rifle with, I think, Great ergonomics. The manual of arms does require a learning curve but if all those German Troops could learn it I am sure you can too. Also while the cheap HK mags are tempting many CETMEs don't like them, if you by a CETME let me know ans I will send you a free HK mag to try before you invest money. I use all CETME magazines, $8.95 each in steel from J&G Sales.
The biggest things to look at on a CETME will be the bolt gap.
Ideally this gap will fall between .010 and .015 with the hammer down.
If it is off of the ideal .013 it can be adjusted some with new rollers but not a huge amount
If you are looking at one of the new CIA guns do not buy it off the shelf at a dealer without knowing when the dealer bought it. The reason is CIA warranties the gun for 12 months ofter it leaves their warehouse so if the dealer has had it 10 month you only have 2 months of warranty left. Find a dealer who will order one in for you. Check the bolt gap before you buy it.
Not all HK parts will fit the CETME but some will. However CETME parts are available as well. My brother bought one that new rollers would help so I installed a new bolt, the new bolt cost $30 and with that I got his gap to .014 and it runs great. I have to admit to an advantage with these guns...I am an HK schooled trained armorer but it simple to work on.
Stay away from the cheap scope mounts. If yu plan on using a scope for the most past buy the HK low mount, the claw mount prevent a proper cheek weld without a cheekpiece. I also had to add a stock extension to gain eye relief on mine.
These are great rifle, accurate and reliable...use a little care picking one out and you will be happy...
Mine in green HK furniture with extension and cheekpiece...