M4Newbie

I am a Benelli newbie. In fact, have not yet purchased my first shotgun. I am just now getting into shooting. Have had a Kimber Pro Tactical II .45 for approx. 2 years and want to get into 3-gun by the end of the year. I am trying to decide between the M1 Practical and the M4. My primary use would be for home defense and 3-gun. However, I would like to also be able to use the same gun for the very occasional skeet/trap shooting outing with friends who are into that, as well as the yearly dove hunt to which I am invited. My main question is whether or not an M4 can be outfitted with a longer barrel, say 26". Does anybody know whether or not this is possible?