True, but if you have the IRL, why bother with any more? The Gatling Gun trick really does work. I do it all the time.
Here's another one:
In Chapter 4-2, after you raise the portcullises that bar the upper door in the gallery with the statues that hang upside down from the ceiling, you'll enter a room with Zealots, including a Red one. If you have a rocket launcher, aim at the upper level, on the left. If your aim is good, you'll hit the crossbow zealot and trigger the gas barrel, killing the Red Zealot. Otherwise, you may have to chase him.
If you do, here're two alternate strategies:
ONE: If you didn't kill Red and you get the cutscene when you jump down to the upper deck, stay there and aim a rocket launcher to the right of Red. If your aim is good, he'll go down. DO NOT AIM DIRECTLY AT RED, or he WILL run and you will not be able to hit him at all.
TWO: If he ran the second time, DO NOT FOLLOW HIM. Instead, drop back down to the lower level and go back through that room you first used to reach the upper level and intercept him.