Indeed. Fix please. The Zafir is such a lovely gun, but I stopped bothering with it (say, while being tempted to pick one up from an enemy) for two reasons:

1. exactly this right here; a lot of the scopes are not usable. And then there is
2. that funny ammo (it's the tracer variant I think?) that doesn't even suit/fit into the weapon. What the...?!

I've seen so many SP missions with guys and their Zafir running around, but unable to shot a single shot for having all but this useless green ammo equipped. LOL. Sucks super hard. :D

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Also see the following tickets (even if already resolved for some matter?):

• 0023785: Zafir's Optics bug. http://feedback.arma3.com/view.php?id=23785
• 0023950: Arco Scope Obstruction. http://feedback.arma3.com/view.php?id=23950
• ... and probably some more :/

oh, and here, this one (assigned, but not resolved yet; then again, this might just be for the mission designers to fix/swap in the new ammo now...):

• 0023306: "150Rnd_762x51_Box" (legacy class for "150Rnd_762x54_Box") can not be loaded into Zafir. http://feedback.arma3.com/view.php?id=23306

That's odd. I'm pretty sure it has never been fixed since Zafir was added.
It is one of my favorite guns too, but I do my best to avoid it because of the scope obstruction.

Btw, all Arma 3 light machine guns fire tracers from normal belts and mags. I reckon it's intended.

Every fifth round is a tracer orso.. That's standard for LMG's.

Yes, so it's not a problem. But the scopes are a big one.
I believe it could be fixed by moving the scope forward on the rail.