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Discussion Starter #1
Are you only looking for the housing, or the entire lower with pack? If you're looking for the complete pack, you'd better try and find one that has not yet been clipped and pinned.

A clipped and pinned factory lower without a registered sear is an illegal machine gun conversion device. And in recent rulings, they've even said that a sear-ready pack, even without the sear, is a no-no.
I'm a little confused...do you have that backwards?

Clipping and Pinning are modifications to allow you to stay within the laws/regulations. How can a c/p'd lower without a registered sear be considered an illegal machine gun device?

As far as an Sp89/Mp5k conversion... How does one legally use a 4position mp5k lower? Acquire a 4position clipped and pinned lower and swap in the Sp89 internals along with an mp5k selector/axle? Am I thinking along the correct lines here?
 

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I'm a little confused...do you have that backwards?

Clipping and Pinning are modifications to allow you to stay within the laws/regulations. How can a c/p'd lower without a registered sear be considered an illegal machine gun device?

As far as an Sp89/Mp5k conversion... How does one legally use a 4position mp5k lower? Acquire a 4position clipped and pinned lower and swap in the Sp89 internals along with an mp5k selector/axle? Am I thinking along the correct lines here?
Actually, clipping and pinning are not done "to allow you stay within the laws." Full-auto packs won't fit onto the semi-auto receivers because the shelf on the receiver is wider than the space between the ears on the front of the lower, where the swing-down pushpin goes, and also, the internal pack frame has a corner that also would interfere with the semi-auto shelf. Clipping and pinning is the act of machining out the inside of the ears and enlarging the hole in the front of the grip frame so it fits over the shelf. That's the clipping part. Pinning is taking a pushpin and cutting the ends off, and then super-gluing them into the grip frame to make it LOOK like there's a pushpin there. Then to make a burst or SEF pack fit, you must also cut out the lower corner of the pack frame so it clears the shelf as well.

And it's not backwards, but I left a phrase out, so I can see why it's a little confusing. When I said "without a registered sear", I should have written "with a factory sear", because that's the way they're usually sold - complete burst packs with the catch and trip lever. In fact, the first used burst pack I bought had already been clipped and pinned. Yes, it was an illegal conversion device. It would fit on the gun, and by holding the trigger down and manually cycling the cocking lever, it would fire in semi, burst, and full auto mode. It was illegal as hell, so it and the gun were never in the same location at the same time until after the pack had been converted to take my registered sear, and even then, that pack was technically a machine gun, all by itself.

To use a registered sear in a burst pack, a few key modifications must be made because registered sears and factory sears (actually called "catches") are not the same dimensions. The key mods are that the catch pivot hole must be moved slightly, and the catch notch in the hammer must be extended.

So... if you were to find a clipped and pinned lower that is otherwise unmodified, even if the catch is missing, you still have an illegal conversion device, because the factory roller catch is not a controlled NFA item. In the eyes of the ATF, since all you have to do to make it operate in full auto mode is reinstall the factory sear, what you have is a machine gun.

Furthermore - they recently ruled that even packs that are clipped and pinned and have been modified to accept only registered sears or "sear ready" are illegal if you do not have a registered sear. I don't think they enforce it quite like they would a clipped and pinned fully factory pack that is 100% operational, but they have made the ruling.

The only way to stay 100% legal is to get a completely unmodified pack, and do not clip and pin it until you either install a registered sear, OR modify it so it cannot possibly fire in burst or full, but if that's all you want to do, there's no point in getting a $500 burst pack. You just need to put an ambi-semiauto pack into a burst housing.
 

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if you have a SP89 and just want it to look like(but still be semi only) a Mp5K, then you need a C/P lower, you can use your SP89 pack in a C/P SEF style without mods(just need the longer selector)

If you want to use one of the ambi style(any of the types with red bullets) you need the trigger pack that goes with it(the SP89 pack will not fit) and it MUST be modified to fit(and be legal), normaly looking at $500 for this combo. Like at the bottom of this page
http://www.hkspecialist.net/clipped.htm

I think I have this right......

I'm a little confused...do you have that backwards?

Clipping and Pinning are modifications to allow you to stay within the laws/regulations. How can a c/p'd lower without a registered sear be considered an illegal machine gun device?

As far as an Sp89/Mp5k conversion... How does one legally use a 4position mp5k lower? Acquire a 4position clipped and pinned lower and swap in the Sp89 internals along with an mp5k selector/axle? Am I thinking along the correct lines here?
 

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Discussion Starter #4
I think I got it

So I think I got this right - for some reason this is so hard to wrap my brain around.

So bottom line if I have a semi-auto reciever.. whatever I get will have to be clipped in order for it to fit. Pinned is a cosmetic mod - that's no big deal.

My options:
1. Take an Sp89 trigger group and put it in a C/P'd SEF lower.

2. Acquiring an Ambi lower with a trigger pack already installed - C/P'd

and I should never:
Acquire a C/P'd Ambi lower with the full auto pictograms by itself without a trigger pack already installed.

What I'm thinking:
I want the option of adding a registered sear later on in life so I'm thinking my best option is to pickup a trigger housing with burst pack already installed?
 

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So I think I got this right - for some reason this is so hard to wrap my brain around.

So bottom line if I have a semi-auto reciever.. whatever I get will have to be clipped in order for it to fit. Pinned is a cosmetic mod - that's no big deal.

My options:
1. Take an Sp89 trigger group and put it in a C/P'd SEF lower.

2. Acquiring an Ambi lower with a trigger pack already installed - C/P'd

and I should never:
Acquire a C/P'd Ambi lower with the full auto pictograms by itself without a trigger pack already installed.

What I'm thinking:
I want the option of adding a registered sear later on in life so I'm thinking my best option is to pickup a trigger housing with burst pack already installed?
Ok, I think I see the disconnect now. It's a terminology difference. Here are the definitions I'm using:

Lower - the entire collection of parts that comes off when you remove the stock. It is the grip frame, along with all internal parts.

Grip frame or housing - the shell of the lower, it includes the grip, but not any of the internal pack.

So - trying to use the terminology I think you are using -
It's perfectly fine to clip and pin what you call the lower, which is just the external housing with the grip. As long as you don't also modify the internal trigger pack to fit the semi-auto shelf, it is totally legal.

You can modify any housing to fit the semi-shelf by clipping it in fact, pictogram, SEF, doesn't matter. As long as you don't also modify the pack to fit. It's really a modified pack that will get you in trouble, not the housing.

So if you want the look of a burst pack, with a semi function, then just get a factory unmodified burst pack, clip and pin the housing, and leave the internal pack in original configuration until you either a) install a registered sear into the internal back or b)modify the internal pack to be semi-auto only legal.

So taking your options you had - 1 is easy. Yes, it works just like that. But 2 is a little tougher to do - ambi packs always have either burst function, or full auto function, except for one - the FBI ambi pack. It is safe-semi only. And I *think* all you need to do is clip and pin the housing, the only one I've seen had clearance for a semi shelf, but I don't know for sure if it was modified because although the FBI ambi group is safe-semi only, it still fits on a push-pin swing down lower. Just check it out with an NFA FFL first.

Make sense now?
 

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Discussion Starter #6
So if you want the look of a burst pack, with a semi function, then just get a factory unmodified burst pack, clip and pin the housing, and leave the internal pack in original configuration until you either a) install a registered sear into the internal back or b)modify the internal pack to be semi-auto only legal.

So taking your options you had - 1 is easy. Yes, it works just like that. But 2 is a little tougher to do - ambi packs always have either burst function, or full auto function, except for one - the FBI ambi pack. It is safe-semi only. And I *think* all you need to do is clip and pin the housing, the only one I've seen had clearance for a semi shelf, but I don't know for sure if it was modified because although the FBI ambi group is safe-semi only, it still fits on a push-pin swing down lower. Just check it out with an NFA FFL first.

Make sense now?

I think so. If I understand correctly I want:

-1 Ambi pictogram 4position 3rd burst trigger housing - clipped and pinned.

along with

-1 factory unmodified burst pack.

This type of setup usually runs about $500 I think?
This will leave me with the ability to add a registered sear later on in life.
 

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I think so. If I understand correctly I want:

-1 Ambi pictogram 4position 3rd burst trigger housing - clipped and pinned.

along with

-1 factory unmodified burst pack.

This type of setup usually runs about $500 I think?
This will leave me with the ability to add a registered sear later on in life.
Yep, you got it now. The used burst packs run about $450-$500. New ones about $600. You can also get the already clipped and pinned housings from hkspecialist.net or hkparts.net (I think) for $150 or so.

One thing to keep in mind - registered sears go up about $1000 or so per year, and have been on roughly that pace for years.
 
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