I've seen AR15 uppers for 6.5mm, 6.8mm and 50 beuwolf. Are these directly interchangable with an AR15 lower? What about magazines, will they all fit in the lower mag well? I'm thinking about trying out another caliber and was wondering if any of you had tried these combinations and what your results were. I know 7.62 x 39 is also another option as well. Any problems with any of them or just stick with the vanilla 5.56?
Thanks....
Thanks....