Or, a copyright violation.

Girsan copies the M&P looks, with a different looking grip.

MC28SA - European American Armory/USSG

It's only a copyright violation if they used the S&W advertising material without permission.

As for a patent infringement -- there's nothing there any longer protected by patent. Otherwise, Colt would be a prosperous company instead of a near-bankrupt, simply by suing the pants off of anyone who makes a 1911 copy. Patents only last 20 years -- after that, it's anybody's ballgame. And frankly, coming up with a gun feature that is patentable is a tough go -- there's really very little new under the sun. Folks just keep coming up with different combinations of the same designs.

BTW, S&W did violate Glock's patent, and had to change their design and pay a hefty chunk of change to Glock.

__________________
Pisgah

But at least S&W didn't try to copy Glock's "aesthetics," thank goodness.