I do not believe that is considered a gun part, and therefore not subject to restriction.
You can go to Brownells web site and look up the parts you want and it will tell you if its a gun part (as far as as export requirements are concerned). If its listed as a gun part, then it must be under $100.00, AND it must also be from an approved manufacturer listed for export with the State Department for it to be able to come across the border without additional permits/hassle, etc.
