Probably your best bet is a good quality AR15. Any of the Colt versions will likely serve you very well for a very long time. I have built some back in the mid 90s, and speaking for myself only, I think one would be wise to buy a name brand, high quality, rifle rather than create a mixmaster. Especially if he has not done something like this before.
I chose the SIG 556 for a dinky bore defense rifle. I am well pleased with the example I have purchased, and feel that it has many desirable features. So far at least it has lived up to my expectations. I seriously doubt that in any forseeable defense situation that it would make any difference what I was using.
It is just that I am not a fan of the AR15 for purely personal reasons, so I chose something else. What I like about the SIG is that many of the design features borrow the best from other designs. The gas system is kind of a combination of the FAL and the Kalashnikov. The iron sights are very much like the HK roller lockers, which I really admire. The short length of Pic rail as well as the magazine well are AR 15 in origin, near as I can tell. The ambi safety selector is much like the FAL in the automatic version, and sort of HK-ish.
The handguards may be unique to this design, I am not sure, but they sure keep it cool, despite several rounds having been fired at a time. No perceptible heat in the fore end.
Altogether I feel these design features make a swell rifle. My example is well made and the parts work together exceptionally well.
Last edited by stubbicatt; November 26, 2012 at 07:33 PM.