I've heard of rifle-length round handguards that are designed to fit a triangular endcap, but am not sure about CAR-length, do they exist? if so, where can I get them?

The reason I'm asking is because I changed out my carbines round handguards/endcap for 607 style triangular ones, both for ergonomic and aesthetic reasons, and have liked them a lot better than the round ones, but more recently I started using a different grip/stance style, for which I'm not sure if the round HG's might actually be better, maybe, maybe not, but without the ability to easily swap them, I can't compare them, and hell will freeze over before I spend another entire day struggling with getting the FSB off to swap the endcap, especially since I'm not even sure whether or not I'll want to go back to the round handguards.

Never mind, they wont fit.