H&K HK MR556/MR223 Incomplete Upper Receiver - Black

I bought the A5 upper in black about a year ago now, and noticed that the thread pitch was different. HK re-worked how the barrel attached to the receiver. You can tell in these pictures here for this "MR 556 upper" how there is now a metal nub that actually sticks out to mate with a slot in the new A5 barrel assemblies, instead of the older style with a separate little pin that can come in a narrow or wide size. Also, the barrel nuts have changed to match the finer thread pitch that this upper has. Just be aware before you buy this that while this part is of magnificent quality, with a fine finish, and definite upgrades from the old design, I have still not yet been able to source the newer 416 A5 barrel assemblies, so you wont be using this anytime soon, unless you take it to a gunsmith and have the threads reworked.