[SovietTwins]

Hi all. I try to use my mr223 upper with bushmaster ar-15 lower, but firing pin can't to strike primer. Any recommendations? Thank you!

 

[frogman342]

Some of the hammers are too short for the HK uppers. Get a hammer that is a little higher, DPMS, and it should work fine.

 

[dwillHK]

There was a similar post on an MR556 upper. The front face of the trigger can't have a notch at the top. It needs to be solid or higher at the top to move the firing pin safety that HK has on their bolt carrier.

 

[pb_removed]

http://www.hkpro.com/forum/hk416-hk...r-top-line-ar-lower-not-firing-need-help.html

 

[SovietTwins]

Thank you a lot!!!

 

[Montrala]

Also look here:

http://www.hkpro.com/forum/hk416-hk417-hq/150796-list-hk416-mr556-mr223-compatible-trigger-groups.html