I'm relatively new to Project and brand new to this forum. I searched for this but realized it's probably such a beginner issue, I'm just missing it.

I have a project that uses normal work hours (mon-fri, 8-5), but have a task that takes 28 calendar days. If I use a standard calendar, it adds weekend days, making it a lot longer than 28 days. I tried using the 24hr calendar for the task, as well as creating a calendar specifically for my task that goes 24/7, but they both yield a Gantt view of only 10 days (the task doesn't have a resource assigned.) What have I missed? I just need a task to show as 28 days, LITERALLY.