[AmericaNL]

Thanks, guys. I knew I could count on you for a short, sweet answer!

At a minimum I will want a .22 upper, but I'm hoping for more flexibility than that. Maybe Sig will help out with more MCX uppers ...

 

[AmericaNL]

Probably the fastest way to egg-out lower pin holes and deadline a lower receiver is to put in a blow-back action .22lr or 9mm upper receiver.

No idea if that kind of thing matters to you guys in Europe and replacement parts and which part is regulated/classified as the "firearm" in your respective nation

Here, with MR556 lowers fetching $1400+ dollars...it's stupid (just putting this out there for the local boys).

Interesting point which I hadn’t considered. Thanks, dms.

I have not tried different uppers, and with this information I am reconsidering. The lower is the registered piece in the Netherlands.

Wlevels, I waited about 15 months for my 14.5 inch MR223A3 to arrive after ordering. I hope you’re patient!

 

[AmericaNL]

That is why I would prefer something like that: HK HK416 D10RS .22 LR - Vismag

Only needs "A3" furniture.

(for reference MR223A3 11" price in Poland is 9900,- zł)

I had one of these for about 2 years and many thousands of rounds. I ran about 12k rounds through it before its first cleaning and was impressed with its reliability, only failing to fire because of bads round (as we have all seen with .22). After that I started feeling guilty about letting such a fun piece get so dirty. The first cleaning was not much fun, as you can imagine. It ran beautifully for the years that I had it and I have fond memories of our time together.

Unfortunately, the Dutch limit to 5 firearms convinced me to sell it, resulting in my original question about different uppers which I can have because the lower is the registered, and therefore limiting, piece.