Completed, compliant, HkParts trigger pack with HkParts hammer, sear, trigger, and trigger box.
All GTG, right? DO NOT WASTE YOUR MONEY ON AN HKPARTS TRIGGER BOX!!!! The MKE ejector won't fit in the channel without jamming. HkParts Sales solution to my problem was asking if I'd tried a German ejector. When I pointed out this trigger box was useless to me since I bought it specifically for my MKE parts, I was provided a link to the return policies. When I requested contact info for the manufacturer, crickets.
Get the RTG US trigger box.
Also, remember to order a non-drilled hammer strut and a semi-auto spring and bushing. You probably won't be able to remove the factory strut from the factory hammer and the US semi trigger boxes aren't set up to re-use your MKE semi-spring.
Attached File


MKE trigger pack above the HkParts box.
Attached File


Upside down MKE box on left, RTG box (a good copy AFAIK) upper right, and HkParts lower right.
Attached File


MKE trigger pack in pieces. HkParts TB
lower left. Note pinned MKE hammer/strut.
Attached File


RTG trigger box. Should've gotten this one to begin with. I did have to cut it to match the MKE box.
Attached File

Completed RTG trigger box. Un-modified. Note "extra" metal on lower right. This prevents it fitting in the MKE lower.
Attached File


Factory MKE sitting on modified RTG box. Note the differences between semi-spring pin placement.
Attached File


Attached File


RTG trigger pack. Note modification on right.
Attached File

I had no issues with my hkparts box fitting my mke rs, I am having trigger reset issues(first test today) but I’ll do some fitting inside the trigger box and smooth it out.

Your ejector lever didn’t jam?
Everything else fit fine in my rs.

It was pretty tight, I just worked it with a bit of oil and it works fine now.

Not mine. I stopped myself from getting the Dremel out.
Bought the RTG box, problem solved.

The HK parts box would accept all the parts, I just got lite primer strikes when I tried to fire it.  The RTG box is far superior and is what I ended up using.

I’m going to try the rtg box for the next mke i need to 922r

I am running 2 of those 2 piece HKparts trigger packs (purchased complete) and have had no issues yet, I was hesistant when I received it and it wasn’t the traditional stamped steel box.

With a factory German ejector, it may not be an issue.