First, metaltechs are CRAP BBs. I bought a bag 2 yrs ago to try them out. They shot worse than flying colors in my G3, they JAMMED another guy's PTW, and they were shooting all over the place.
Second, high quality BB nothing. If your a good guntech you can run shit BB's in any gun. I've heard dozens of people talking about how flying colors are crap and they jam stock guns, and they jam upgraded guns, and they jam mags. I've shot over 20 bags of flying colors and not once have I EVER had a jam in any of my 6.03 tightbore barrels.
Third, my 249 gets the same range as my M4, which is about as good of a range as you can get out of an AEG using .28s