Can 100% Real Lime Juice be substituted for Key Limes?

It will be fine. I usually use the bottled juice myself and it still tastes great.

Key limes have a rather unique flavor that has never reminded me of Real Lime Juice. You could certainly try (lots of people have differing opinions of the “perfect” key lime pie), but I wouldn’t base my main desert on it. Maybe try adding some fresh lime with a few TSP of zest to balance out the flavor and get that hint of bitterness.

If you do decide to give it a shot let us know how it turns out!

Yes. Personally I would use lemon juice because, to me, key limes taste more like lemons.

It will taste a bit different, not exactly like Key Lime pie, but I’m sure it will be very good.
Let us know!

Your pie won’t be green if you didn’t get some limes. It is the zest of the lime beaten into the egg yolk until your hand falls off that tints the pie green. You’d be much better off getting some limes and zesting them then squeezing the juice. But your current plan won’t ruin the pie. It just won’t be all it can be.

What recipe are you using?

I’m using this recipe:
http://www.epicurious.com/recipes/food/views/Key-Lime-Pie-351876
minus the almonds in the crust

And I’ve used the zest and juice of two limes and then used the bottled juice to get the remaining ¾ cup of juice.

You should be fine then—it’ll be totally tasty.