Have 2 FN-49s. Both 7mm. One of them is unfired and still covered with cosmoline. That said, wiping a surface down with a paper towel WILL NOT get rid of corrosive salts from the primer. (I don't know why you'd be shooting corrosive ammo anyway.) Aside from old GI bore cleaner from ww2 or Korea, good old soap and water is the best way to dissolve corrosive salts...and yes, you'll need to clean the gas system. If you haven't fired it in a while and you were able to wipe off corrosive salts, you might as well just chuck it because the bore is toast. You have to clean IMMEDIATELY after using corrosive ammo.
While on the journey to getting my PAL, I really wanted one of these. During that time there was the upheaval of the OIC bans, and when I finally was able to get one the price had risen by 50%. Of course it's even more expensive now.
If you're a reloader that can't find 8mm brass, you can convert 30-06 brass to 8mm Mauser. Just cut down the 30-06 brass to about 2mm longer than standard 8mm Mauser trim length then size the 30-06 brass to 8mm Mauser sizer die.
Is this FN 49 available in any other ammo. size than 8mm? I notice that you keep saying "lightning" when you actually mean to say 'lightening' as in weight reduction, don't you?