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Can someone explain the whole push pin lower thing to me? I just bought a DJ Getz DF89 pistol that I will SBR. It has no push pin lower and uses a shelf.
The MKEs that are going to be imported have a push pin lower. I don't understand why some do and some don't.
Sorry for the noob question but I'm an AR guy finally getting over to the HK market since there are a lot more builders and options now than there used to be years ago.
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"Back in the day" every semi-auto HK had to have the shelf, which is a semi-auto restrictive/blocking shelf.
Let me backtrack...
The first ever HK semi-autos imported here had pushpins, like the HK41 (and anything HK4x). I don't know how many were brought in;
Wiki says 400 or less. They are super-scarce.
ATF almost immediately declared the pushpin to be no good, because the receiver is "too similar" to a select-fire receiver. "There HAS to be 'mo difference!," they said, so the modern shelf was born. This became the HK91 (and HK9x), and all subsequent clones' pattern until a few years ago. It physically prevents one from attaching a factory select-fire anything. (So did the earlier one, basically). Even if you use the factory-supplied trigger housing from the 91, which your select-fire pack could drop into, it now cannot attach to the receiver because the front-bottom corner is in the way when it hits the shelf.
It's not May 1986 yet, however, so then machineguns happen...
There were different ways they were converted, but in brief, third-party sears [most commonly] were used. They pivot in a location (pin hole) that is aft of where the factory sear/catch would be located, thus circumventing the physical restriction.
There's also the (much simpler) way of just chopping off the corner of a factory select-fire fire control box (aka trigger pack or just pack). This was not commonly done, due to limited availability at the time.
There's also having a "clipped-and-pinned" housing which will fit on the shelf, and is original select-fire dimension on the outside. These were the rage because they look legit. The packs were still semi-auto (unless you have a registered MG to go in there), and the blocking shelf was still in place. Zero receiver modification.
You could even do a paddle mag release (with ATF-approved modification to the receiver. ~No permanent hole all the way through.) This was, for a long time, the height of HK clone awesome.
The cool kids could even swap their registered MG pack/sear conversions into and out of these independently-semi-auto "hosts" whenever they wished, and they always looked the same (like factory HK military models) on the outside.
The MKE clones a few years ago were the first time (I think) that ATF ever allowed a variance to the shelf idea. There was still a restrictive rear protrusion/shelf, but the sides were narrow like original HK dimensions (so no need to clip/pin a select-fire housing in order to attach one; it just had to have an opening in the unseen frontal area to clear the restrictor shelf.) The restrictor would still block an unmodified select-fire pack from fitting in said housing(s). They even had paddle mag releases
from the factory pivoting on (at first the ACTUAL same bushing as select-fire guns use WITH dummy pin glued in, and later a larger-diameter solid pin welded in place on one side). So this was cool. As a trade-off, the MKE guns were required by ATF to have a blocking piece welded into the bolt carrier channel in the receiver, which prevents a select-fire carrier from being installed. (The "trip" hits the blocker and stops it from being inserted).
With the earlier MKE ones, sometimes the glued pins would fall out. Then your slightly modded housing could actually be pinned with a real pin. Most were afraid to ask ATF if that was OK. (Letter writing is dangerous FYI).
So then POF gets approval to import the POF-5 with an actual pushpin already in the housing/receiver. I believe they too have the restrictive protrusion going into the housing like the MKE. They definitely have a similar/identical bolt carrier block.
Now the new/current importer of MKE (Zenith) got the same approval.
So cool! Now we can buy clone guns with with push pins!
This has led to more questions, such as:
"If it's legal to import them this way, can't I build one the same way in my garage?"
"What do I have to do to legally install my <insert MG conversion device> into it?"The answers I've been browsing seem to say that if you mod your MKE/POF into the "old-school" semi-auto config, where it has NO push-pin hole of any kind, a big wide shelf, and NO bolt carrier block (after the shelf is swapped of course) then it's now legally/physically the same as any other legacy semi-autos out there.
I don't know the answers to other questions.
It would seem that what is legal to import what be legal to manufacture domestically, you know "equal protection under the law" and all that, but the ATF is not known for making sense, and I have not been following the situation that closely, hence my question on page 2 of this thread.
The spring-loaded carrier trip, to circumvent the block inside the receiver channel, is an idea that popped-up (pun intended) in the last couple years, from some clever members of the hkpro forums.
That's basically my recap. I may be mistaken about the factory HK91 housing (only / by itself) being able to accept a factory select-fire pack, but any clipped/pinned housing definitely can, and they are both considered legally unrestricted as far as that goes. If it (the entire firearm) IS full auto, there's (at least) one piece somewhere that is considered to be a MG. All the physical and historical variations can make things somewhat confusing. Then you get into the "wrong ways" people made/registered MG's. That's almost a whole other story. lol
Makes for interesting reading.
Linkies:
http://www.hkpro.com/index.php?option=com_content&view=article&id=141%3Athe-complete-reference-on-the-legal-nfa-conversion-of-hk-firearms&catid=4%3Aspecial-topics&Itemid=5&limitstart=2http://www.hkpro.com/index.php?option=com_content&view=article&id=141%3Athe-complete-reference-on-the-legal-nfa-conversion-of-hk-firearms&catid=4%3Aspecial-topics&Itemid=5&showall=1http://www.hk94.com/hk/topic/6337-heckler-and-koch-sear-faq/