Good guns.
Prone to slamfire with commercial ammo (soft primers). Google "gunboards + MAS firing pin mods"
Kelt talks firing pin mods here...
The .308 can be made to run reliably so long as the chamber itself isn't hopelessly fucked.
Quick and dirty fix involves replacing the recoil spring with a new full-sized one from Numrich ($12) , polishing the chamber, and maybe installing an adjustable gas valve ($25) made by Starmetal over on Gunboards.
A more in-depth approach can be found in an American Gunsmith Article, May 2005, by Russel Corbitt:
Here...
...and continuing HERE...
Note: It is not my photobucket account, and my apologies if I have overstepped––I just found the article by googling, Kudos to Team Tumbleweeds.
The easiest way to tell the 7.5 French from the converted .308 at a glance is to inspect the front handguard. The vent hole toward the front of the handguard should be set back a bit (3/4"?) from the metal clamping band. On the .308 conversions the vent hole it is right next to the band, because Century had to cut back the handguards to fit.
Used to be you could find MAS 49/56's for $250 - $300, but the price is definitely creeping up. Still, $500 seems a bit steep (not that the rifle isn't worth it), but try to beat the guy down to $375. He might bite.