The frame is a replica of a real steel frame. Strayer voigt and Strayer tripp international to be exact (Sandy Strayer was and still is part of both companys). They use a polymer grip to save weight because you dont necessarily need to have a frame that houses the support structure of a grip. Thats the whole advantage of those guns. Weight saving because the polymer is lighter than metal. And its fine because all the high stress areas are in the upper which is made from metal.
Scroll down to competition frames.
http://www.sviguns.com/1101.php?indx=13
Looks a lot like our hi capa frames doesnt it?
Anyways grips should be fine to import. Rule of thumb is that any part that on a real gun that would have a registration or serial number is usually a restricted part. IE we cant easily get them in. Yes there are ways, but this section of the forum isnt the appropriate area for that discussion.
Thats why its hard for us to get frames for pistols, and lower receivers for our rifles.