Excellent choice, sbach.
Keep your Colt lubed, use quality magazines (PMAG's) not aluminum or steel mags, and you shouldn't have any problems. Contrary to all popular belief, the carbine doesn't need to be sparkly clean, but you absolutely must use proper lubrication or you will have problems. If you feel the need to religiously clean something so that all is right with the world focus your attention on the barrel, chamber, and bolt face.
Remember that all mechanical devices eventually fail and purchase replacement parts to deal with eventualities. I would purchase a complete bolt, a firing pin, and a spare buffer spring at a minimum. You can buy an entire BCG if you wish.
If you plan to use the carbine as more than a range toy, invest in a quality sling like a Blue Force Gear quick-adjust two point or something similar.