I rarely consider resale value when buying or building a "modern day" rifle. I know going in that I will probably never get my money back. Breaking even would be the goal that is rarely achieved. Yes there are some cases I've actually made money, and lots of it, but rarely on a "modern" gun. I've done well buying old milsurp long ago and selling later on but thats a whole different area. As far as my AR15's and AR10s go, I bought/built them without regard as to what I will eventually lose on them. I got them because they filled my then current "desire" to have a weapon like that. I think I have about 10 of them now, all different configurations, some impingment and some pistons, SBR, carbines, rifle, varmit/sniper types etc. My current yearning is to build one with my own custom engraving on it. Like the others, I know already I will never get my money back on it. That being said though, I've done the best on resale with factory Colt's as long as they are kept in excellent original condition and sold private sale, not to a dealer. Beat on them and scratch them up and the resale value drops off quick. On rifles I've customized, I've done my best by taking off the add-ons and selling them seperate and then selling the rifle with its stock parts back on it, if they are still in my possesion. On the Colt's I've sold in the past, I broke even on each one except for one I actually sold for more than I paid for it. The secret was that all of them were bought used to begin with, I got them for a decent price, they were in like new condition and I kept them that way while I used them so selling them for what I had into them was not to hard to do. I also have some RRA and Armalites but I doubt when I sell those that I will be able to do the same thing as I bought those new. Like it or not, Colt has the name and with it the value. They may not be the best out there anymore but they seem to be the best when it comes to resale. Just compare used gun prices in gun store racks or online.