I am far from an expert on roller delayed semi autos & machine guns. It would appear that the Century Arms /MKE Imported MP5 clones are equip with an "unregistered sear" in their SEF packs? I confirmed this with a Century Arms AP5 at my local gun shop, as well as a Zenith clone owned by a friend of mine. It is a part that is identical to the hundreds if not thousands of "HK Sears" registered as machine guns under the NFA! The trigger pack lacks the sear trip lever, 3 position selector. MKE receivers do have a F/A carrier block welded in place to justify the 2 push pin trigger packs. With ATF constantly changing their minds, and raiding people for drawing "pictures" of F/A parts on a credit card size piece of metal. It just seems like owners could set themselves up for a constructive possession charge by a over zealous ATF agent!

The trigger pack housing is modified to prevent F/A parts from fitting.  Disassemble and look closely at the safety selector pivot bearing and internal weldments.  This and the sear trip block on the receiver prevent easy conversion.  This is a non-issue and was discussed and vetted when Zenith began importing years ago.  Its actually easier to convert an SP89 or HK 94 than convert a current MKE gun.


18Z50

 I know the MKE have a F/A carrier block that allowed MKE to be importable with the 2 push pin trigger packs. I guess my concern is not about the MKE clone itself, but if you had another clone that didn't have those blocks you could risk being charged for having an unregistered machine gun by an overzealous ATF agent.

The “H&K auto sears” which are registered under the NFA are most assuredly NOT the same as factory H&K auto sears, they are significantly different dimensionally. An H&K registered sear is a CONVERSION sear, which is designed to convert a semi auto into a full auto. They are installed into a SEMI AUTO H&K trigger pack, taking the place of the “elbow spring spacer” in the semi auto trigger pack. The semi auto trigger pack has a “notch” at its front, which allows it to fit onto a semi-auto receiver. The conversion sear, semi auto trigger pack, and semi auto receiver dimensions all work together to facilitate full auto function in a semi-auto H&K rifle or pistol.

The factory H&K full auto sear will not fit or function in a semi-auto trigger pack, and a factory full auto trigger pack will not fit or function on a semi auto receiver. Semi auto receivers all have “blocking shelves” to one extent or another, which physically “block” the installation of the factory full auto pack, with its factory auto sear. If you modify the semi auto receiver and/or the full auto trigger pack so that they fit together, you have just manufactured a Post 1986 machine gun.

The factory H&K sear is not a full auto conversion part, it is just a part. In the MKE guns, it functions just like the “elbow spring & spacer” do on the legacy H&K semi auto roller locked firearms. It was a somewhat unusual choice for MKE to manufacture them this way, but it is a non-issue.

Learn something new everyday. Thanks