Greetings,

I currently own a registered HK sear, which is installed in one of the
original "SEF" type packs.

I would like to run it in one of the newer "Ambi" type packs, e.g.,
http://www.hkparts.net/shop/pc/HK-Semi-Auto-3-Position-Navy-Trigger-Group-89p155.htm

Any suggestions for a good HK smith who can either sell or modify
one of these for me?

Thanks!

SD

There are loads of them.

Mike Otte/Michaels Machines
TSC
RDTS

Those three come to mind immediately.  I had MM do mine.

Those guys may or may not have the parts needed in-stock.  You may have to buy a pack and send it to them along with your sear to have it modified and set up.  I'm not sure what to tell you on how to handle your old pack though, since it's not a good idea to have two modified FA packs with one sear.

TPM

If you want a "clean" install, you will want these two parts.

http://www.hkparts.net/shop/pc/HK-MP5-MP5K-9mm-Ambidextrous-Navy-Trigger-Pack-88p16971.htm

http://www.hkparts.net/shop/pc/HK-3-Position-0-1-F-Navy-C-P-Grip-Housing-242p162.htm

then add L&R selectors.

I guess I don't understand why this would be a problem; honestly, my plan was to be
able to run it either way, at my discretion (e.g., Ambi OR SEF).

The modified FA pack (minus the registered sear) won't fire FA.  Further, it's my understanding that
the "normal" FA sear (like you might just buy from HK parts or somewhere) won't work in
the modified pack, b/c the sear pin hole has to be moved... they don't just grind the
shelf off and send it back.

But if there's an official ATF rule on this, I'd certainly like to see it...

Someone I'm sure will elaborate, but the basic premise as I understand it is that modifying the pack makes the pack itself a conversion device for fullauto.  Now that's fine when you have a sear to put in it, but having extras iirc is a no-no.  They consider that two conversions devices at that point.

And for a while, that was allowed or at least tolerated.  People would do the sort of thing you suggest, and it was easy to just buy already converted packs from people to install the sear into.  You didn't have to buy a new one and have it converted for your sear.  That all changed a few years back.

I'm not sure if there is a ruling on it.  Someone can answer that.  If you're in a hurry to know, ask the people on HKPro and you'll have an answer quick.

Thanks for your reply.  And no, I'm not in a particular hurry, especially since this new (to me)
legal wrinkle turned up.

I actually spent quite a bit of time researching sears and packs (before buying), and one of
the big draws of a sear was the flexibility (or so I thought)-- SEF, burst, etc.  I suppose that the other
thing that surprises me so much about this is that the country is awash in cheap SEF packs
(e.g., $85 here-- http://www.robertrtg.com/store/pc/G3-SEF-TRIGGER-GROUP-LIKE-NEW-40p2067.htm )
...which are readily available and might in theory be converted to run in a semi gun with
the most minimal of tools or mechanical skills.  Given that I can't imagine very many G3's
in U.S. civilian (or police or U.S. military) hands, how is it these parts are allowed for sale so willy-nilly?!?!

That said, I will most certainly abide by the law.  Seems now to me that I probably just need
to decide what style pack suits me the best and commit to that single choice long-term... not worth the hassle
of shipping/insuring a sear off to an SOT every time I want to change style of lowers.

Thanks again for the input........

The issue with a prepped pack without a sear is that on the auto position without the conversion sear installed the hammer will follow the bolt home when set to the auto position.

There are a couple of different ways trigger frames were set up but the more common method was that the semi-auto trigger stop pin was milled out.  This was the little stud on the right inside of the pack that only allowed the trigger to be pulled back so far on a semi trigger frame.  There is an analogous trigger stop on the factory full auto frames that is higher up in the pack which allow the trigger to be actuated enough to clear the semi-auto disconnector out of the way of the hammer.

In addition to milling out the semi-auto trigger stop, the semi disconnector is usually ground down for clearance in use with the modified elbow spring, and obviously the sear trip lever installed.

Think of a modified pack without a registered conversion sear like an AR15 with all full auto internals but with the DIAS removed.

Personally I think HKs are a bit different than AR15s as the firing pin is spring loaded (with a pretty robust spring) that should rob a lot of energy out of the hammer falling home with the bolt carrier.  So in my estimation your odds of a slam fire on a HK are generally reduced compared to those guns with a floating firing pin.  However the ATF frowns on any gun or pack where the selector can go to a 3rd position and have the hammer follow the carrier home.

The easiest way to return a SEF prepped sear pack back to a semi-auto only pack is to remove the trip lever and weld the semi-auto trigger stop pin back in.

I mean, a shoestring can make a gun full auto in about 15 seconds.  Anyone with a drill press can put a third hole in an AR15 lower and install a full auto fire control group in under 20 minutes.  Doesn't make either one of them legal to do.  And none of those parts are regulated.  You can buy an AR15 FA FCG w/ autosear without any paperwork.  It's not contriband until you drill that third hole.  And then you're fucked.

Just because something can be done easily doesn't make it legal, or necessarily something that needs to be controlled in terms of parts.  You can buy them, but you better not modify them to fit into your gun or your gun to fit it in unless you have the stamp.

HK Sears ARE versatile, but they aren't plug and play.  The advantage of a sear over a DLO box or registered pack is that if you want, you CAN swap the sear into a different style pack.  But it's not as easy as simply dropping it into one of a number of spares you keep.  You can only have one type of modified pack at any given time.  It's like a DIAS rifle host.  You can drop the RDIAS into any properly-killed lower, but it won't function until you have a FA FCG in it and you has better only have that in one gun, not all.

These things aren't plug-and-play

I thought about this too, going from my SEF to a Navy.

I was talked out of by a HK smith because as he put it, the SEF packs are bulletproof and the ambi packs seem to have more problems

What are your guys thoughts?

Well the burst packs are certainly more complicated, but I have never heard of an ambi box breaking, ever. I have 2 sears in ambi packs, no problems. Of course, if I was not left handed, I would have been happy with the SEF pack.

I have my sear installed in a 4 position burst pack.  So far at least (15 months), I have had no issues whatsoever.