Why does such a great and expensive rifle come with a trigger that is this terrible?  I love this rifle and the trigger, when it is not slapping your finger is really good. Will this break in or do I need to search for a replacement trigger?

My 5.45 seemed like it had some at first but it went away after a few mags. Or I got used to it,. Which is unlikely. Also go buy a KnS piston and thank me later.

Thanks Scout. I didn't notice it much if I wore a cheap pair of gloves.

Trigger slap on an AK is almost always caused by the wrong rear trigger guard rivet being used, not the actual trigger. I'm not too familiar with the newer Galils, so I don't know what that rivet looks like, if it even exists on the Ace. This is also the reason the US made disconnectors have the tail shaved off.

Link to the proper rivet

https://ak-builder.com/index.php?dispatch=products.view&product_id=30327

Like I said, I don't know what the Ace is using here.

Trigger slap on an AK is also caused by incorrect geometry or machining of the disconnector. Picture this...after firing, the bolt carrier goes back, pushing the hammer down. Because you're still holding the trigger, the hammer is caught by the disconnector, which pivots inside the trigger trough. If there is not enough room for the disconnector to pivot back independent of the trigger, the only thing it can do it hit the back of the trigger trough or the rivet and push the trigger down so the hammer can get hooked. The rivet being the culprit would be somewhat rare since the entire mechanism is at its furthest from the rivet when you pull the trigger as everything is tilted forward. Anyway, that causes an abrupt "slap" forward on the trigger face = trigger slap. As you said though, aside from using the right rivet, removing the disconnector tail is one way to eliminate this problem.
You can test your gun easily and see which situation you're having. Field strip your gun and operate the FCG by hand. You should be able to see at what point your trigger is being pushed forward when it shouldn't be.

I'll take a look.

My Galil ACE 7.62x39 pistol has zero trigger slap. In fact, it’s the best AK trigger I’ve ever used. I would call IWI.

I have this problem as well.