A 4" Threaded 1911 isnt going to be happy with a Suppressor attached. They are running on the border of reliability when tuned without a Suppressor.
If you have a non Bushing 1911 then its best not to suppress it at all. If its a std bushing barrel a Briley Spherical Bushing will assist in keeping the gun tight but functionally reliable.
If you decide to go a Storm Lake is the starting point. It will need to be fit to the bushing and slide. Often the ramps need work and the springs have to be messed with.