Not sure what model you refer to as a MP5KA4 but if it was made by Heckler & Koch:
'HK' will be stamped into the top of the receiver between the scope mount points,
'MP5K' will be stamped into the top of the receiver between the rear scope mount and the rear sight,
The symbol of an eagle with the letter 'N' below it will follow 'MP5K',
"Made in W Germany" or "Made in Germany" will be stamped into the right hand side of the magazine well, along with the name of the import site.
Mexico and Turkey also produced MP5 lookalike copies.