[Dima]

Does anyone have experiences with different caliber uppers on an MR223A3?

In NL, I am limited in the number of firearms I can own (5), but I can have any number of uppers for a single, registered lower. Specifically, I will be considering a .22, 7.62x39 and perhaps a 9mm upper.

Thanks in advance for any advice!

aehm i don't know if the mr223 a3 lower is compatible with a standard ar15 upper - you might have to ask HK directly or somebody from europe who knows that - i just read that on some versions of the mr556/mr223 the pinhole placements are different than on standard ar15 lowers - some brands in europe like DAR offer compatible uppers - but i'm not 100 % sure on that