Which one is better? Inch or metric? Why?

My understanding is thus: inch receivers accept both inch and metric mags; while the reverse is not true. Also, I hear that metric parts and magazines are more commonly available. I know nothing about ammo compatibility between the two.

However, I do not own an FAL mysef; these are anecdotes from a buddy.

its the same ammo....

The major differences are:

Inch sights are taller, so you can't mix and match.

Inch and metric FCS parts don't interchange.

Furniture isn't really interchangeable unless you try really really hard.

Metric mags work in inch guns because the locking tab is smaller. Inch mags will not fit metric rifles.

All inch parts are more expensive, and some are getting hard to find. 922r parts are not as common for inch guns.

Now for the common parts:

You can put inch or metric barrels on either inch or metric receivers. Inch builds require an extra part to get the barrel to fit correctly.

You can use both inch and metric lowers on either receiver as long as you change the rear sight ro match the front. The rear sight is part of the lower receiver on an FAL.

go metric...cheap parts cheap mags and readily available

I own an inch pattern, and I have to say that I love it, but for general consumption/use, I would recommend metric, mainly because of mag prices and availability of parts. Check out both while you can and decide what you like best.