OK not real clear on your question but I will take a stab at an answer for you
Most cap embroidery is limited by the Cap not the frame unless your using an older Window Style frame or a home style machine that does not have a true cap frame system.
If your using some home machines you can now get the Dream Frame Hat Hoop from Hoop Tech Products and it works great on commercial equipment and I have heard people like it for home machines as well.
I have very limited exposure to home type equipment so I cannot comment first hand.
If your seeing caps in retail stores where the embroidery goes all over the cap then your looking at embroidery that are done BEFORE the cap is made as a panel program where the embroidery is done on flat material not a finished cap. There are companies you can do that with but not in low volume.
If none of the above applies give us more detail on what you using equipment wise and maybe we can help more.