Noob question

[deerollman]

how does one affix a scope to a fal? do you need a special receiver cover?

[brownknees]

Yes. That's how it's done.
Essentially there are 2 styles. One bolts to the upper reciever, replacing the normal dustcover, and the other is a slide in type using the rails for the normal cover.
Both have a advantages & dis-advantages, so it's kind of take your pick.
DSA makes the best known bolt-on type which is rock solid & has a weaver/pitcanny type rail built in to the solid alloy cover.
Removing any bolt-on does not retain zero.
ARMs, or Grenadier precision both make slightly differing slide in types, again with a moulded/machined in rail.
These do hold zero when removing & replacing.
The bolt on types will mark the finish both inside & outside the upper reciever.