I shot sporting clays with my M4 for several years. My father-n-law has a dedicated Franchi that is better suited but I still had fun. Then late last year, since I enjoy it and we have been going a lot, I found a great deal on a 12g Cordoba and had to jump on it. I do pick up more birds with a proper tool but I still have fun either way.
On a side not, the first time I went out the gal at the range asked if I had a gun or needed to rent one. I showed her my M4 with pistol grip stock and side saddle. She responded "that's not going to work". I said sure it will, every time I pull the trigger it goes bang. LOL Some people are a little to serious.