I was on the fence about picking up a new AR or Mini 14. Decided to build an AR to save a little but now I'm more at the budget be damned point. Now my hang up is if I should go for a gas piston design or not. I've seen a lot of pros and cons and would like to see you guys weigh in. I'm going for a pistol configuration. 7 1/2 barrel with an extended rail system and A3 type stock rather than the short pistol buffer only. So if I go the piston route I'm not sure if it would be better to go the way of a factory built upper that already has a gas piston system rather than building my upper. My lower is complete. I have experience from my military days in building ARs from M-16s to M4s to GAUs, but never built or worked with a gas piston system other than working on AKs here and there.