I agree, as well, probably Colt.
There is a sure way to spot Ropers. The jig holes in the back of the grips are square. It looks like you have that. There are a couple of other identification factors, which I will not mention, due to the increased risk of forgeries occuring. Rest assured, those factors are present in your grips as well.
Roper grips were all made by an employee, a Mr. Gagne, who was a master craftsman, and had worked for S&W. Roper was a salesman and sold the grips made by Mr. Gagne and called them "Roper" grips. the grips were actually made to fit the customer's hand. An outline of the customer's hand provided a guide for Mr. Gange.
Roper was born in Amherst, Massachusetts in 1881. Both his father and his grandfather were involved with the gun industry. In fact, his grandfather was awarded the patent for the choked shotgun barrel in 1866. The Roper men referred to themselves as engineers, not gunsmiths, which may imply something about how they viewed the trade. Roper attended prep school at Worcester Academy and graduated from MIT in 1903 with a degree in mechanical engineering. In 1918 he moved to Springfield and that is when his dedication to pistol shooting, experimentation and competition really began in earnest. Springfield was the home of the U.S. Armory and the Smith & Wesson factory and Roper soon established himself with the leading pistol and revolver shooters of the day—Colonel Roy D. Jones, General Julian S. Hatcher, J.H. FitzGerald, Captain Charles Askins and others. This clubby group really moved pistol competition from near non-existence to equal status with competitive rifle shooting in the 1920’s and 1930’s.
As an author, Roper contributed numerous articles to The American Rifleman magazine and wrote two books in the 1940’s. Pistol and Revolver Shooting was published in 1945 and Experiments of a Handgunner was published in 1949. He also co-authored Smith & Wesson Hand Guns with Roy C. McHenry. For many years he was the Sales Manager (later VP) for Smith & Wesson. During WWII he formed an engineering firm—Roper and Broderick—and did consulting work for other gun manufacturers. He died in 1954 at the age of 73.
Here is my Official Police in .22LR with Ropers.