he AR-15 is one of the most popular and customizable rifles in American history — and for good reason. Its modular design means no two builds have to be alike. Whether you're building a precision long-range rifle, a home defense carbine, or a competition-ready flat shooter, the AR-15 platform can be configured to meet your exact needs. But why should you bother with a custom build when you can walk into a store and pick one up off the rack? The answer is simple: off-the-shelf rifles a …