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hk rifle making f/a to s/a mininum to legalize

5065 Views 32 Replies 11 Participants Last post by  scottinthegrove
if you had a kit hk rifle that you wanted to sell and they basicly come f/a can you just mill the slot in the bolt and keep the f/a trigger pack with a c&p housing and just to make sure i am thinking right you cannot remove the shelf on the mag housing to make a f/a grip frame with s/a parts or other wise made to semi(i am allmost positive you can't) because all the kits send you a f/a pack that does not fit anyway what is the best and cheapest way to put a s/a grip/pack in its place and can i just mill bolt or do i have to do both sorry i know i 'm prone to rambling thanks men
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I might as well chime in with my opinion too. Full auto bolt carriers are fine now. Colt worked that out with ATF because they wanted to just make the one type and the HK clone makers followed suit behind the AR guys. I've always heard that full auto trigger parts with a semi were considered constructive possession so could get you in trouble. The AR won't work without the machining for the sear so you could put those parts in but it's still a semi. I wouldn't want to be the test case so I think I would advise against keeping semiauto weapons and full auto triggers in the same place.
There is a difference between HK and M16 FC parts however. With a DIAS, M16 parts will enable select fire in a semi platform. The HK parts must be physically altered to get a semi to function selectively. That is manufacturing and requires licensure and registration.
There is a difference between HK and M16 FC parts however. With a DIAS, M16 parts will enable select fire in a semi platform. The HK parts must be physically altered to get a semi to function selectively. That is manufacturing and requires licensure and registration.
I don't get where you're coming from. A drop in auto sear is just like a DLO trigger box. All you need is the FA trigger group and carrier in both cases.
I don't get where you're coming from. A drop in auto sear is just like a DLO trigger box. All you need is the FA trigger group and carrier in both cases.
I'd like you to demonstrate how a FA trigger box fits in a semi receiver. For this to happen, 1 of 2 things has to be true: FA box has to be illegally modified to fit OR receiver has to be missing the semi-auto shelf and be an illegal MG.
I'd like you to demonstrate how a FA trigger box fits in a semi receiver. For this to happen, 1 of 2 things has to be true: FA box has to be illegally modified to fit OR receiver has to be missing the semi-auto shelf and be an illegal MG.
A DLO trigger box is LEGALLY modified to to fit a semi receiver shelf and uses all german FA trigger group. Do a search for DLO trigger box and you'll get a couple hundred hits explaining this. Even a registered HK sear fits a semi pack without any modification to the gun.

The funny thing is that drop in autosears were designed to fit early Colt AR15s so most other ARs must be milled out to accept the DIAS. So really the AR15s have to be machined, not the HKs.
The HK parts must be physically altered to get a semi to function selectively. That is manufacturing and requires licensure and registration.
A DLO trigger box is LEGALLY modified to to fit a semi receiver shelf and uses all german FA trigger group.
I totally get the legal side of how it works. We were talking about a semi receiver with a factory full-auto pack. If you have a DLO pack then it's a legal MG and you're good to go.
Mt162

The difference is that a DLO pack is a registered NFA item and can be used in any semi HK gun that it will fit in. The pack is the registered machine gun. I have an SP-89 that was re-worked into an MP5K-N semi gun. When I purchase a registered DIAS or a DLO pack for that gun. It is the seer or the trigger pack that will be the registered machine gun. The host being a semi-auto doesn’t matter at that point. Does that make any sense?

Sean
The AR won't work without the machining for the sear so you could put those parts in but it's still a semi. I wouldn't want to be the test case so I think I would advise against keeping semiauto weapons and full auto triggers in the same place.
The funny thing is that drop in autosears were designed to fit early Colt AR15s so most other ARs must be milled out to accept the DIAS. So really the AR15s have to be machined, not the HKs.
I own a DIAS and a Fleming HK sear. My low shelf AR receivers include Bushmaster, Yankee Hill Machine, MGI that can be used with a DIAS without any machine work. I had the steel sear block removed from a pre 94 Colt 9mm lower to make a Colt 9mm subgun with my sear. Other than removing the sear block, no machine work had to be done to the aluminum receiver. There is a complete list of receivers that are low shelf posted at AR15.com.

I'm not going to take the time to post all the modifications that need to be done in both platforms between full auto use and semi auto use. I would however suggest, if someone doesn't know the actual details, it is fine to post guesses as guesses. But to post incorrect information as fact doesn't seem like the right thing to do, at least to me. YMMV.

Scott
I own a DIAS and a Fleming HK sear. My low shelf AR receivers include Bushmaster, Yankee Hill Machine, MGI that can be used with a DIAS without any machine work. I had the steel sear block removed from a pre 94 Colt 9mm lower to make a Colt 9mm subgun with my sear. Other than removing the sear block, no machine work had to be done to the aluminum receiver. There is a complete list of receivers that are low shelf posted at AR15.com.

I'm not going to take the time to post all the modifications that need to be done in both platforms between full auto use and semi auto use. I would however suggest, if someone doesn't know the actual details, it is fine to post guesses as guesses. But to post incorrect information as fact doesn't seem like the right thing to do, at least to me. YMMV.

Scott
You took my quotes out of context. My first quote was related to the poster that said an m16 trigger, selector and carrier would make an ar15 full auto in 15 minutes. I was stating that it will not and you need the rest of the parts including the trip for it to work. The machining would be required for an original m16 sear because that poster was not talking about a registered trip at that point. The DIAS post came later. Are you saying you can buy an AR15 milled and drilled for an original m16 autosear?

My second quote said MOST ar15s won't accept the DIAS without machining and then you said the same thing by stating low shelf will and high shelf won't. You said the same thing I did in different words.

So what is so incorrect about my posts?
Mt162

The difference is that a DLO pack is a registered NFA item and can be used in any semi HK gun that it will fit in. The pack is the registered machine gun. I have an SP-89 that was re-worked into an MP5K-N semi gun. When I purchase a registered DIAS or a DLO pack for that gun. It is the seer or the trigger pack that will be the registered machine gun. The host being a semi-auto doesn’t matter at that point. Does that make any sense?

Sean
Yes, I completely agree with you. That was the point I was trying to make but it got all fuddled up with legal and illegal parts, etc.

1) A registered fleming sear of DLO box is plug and play with no machining required just like other posters say a DIAS is on an AR15 with the fcg. I just was trying to point out that both families of weapons are pretty equivalent in that regard.

2) If I had a semiauto and no registered sear, etc, I would not reccomend having the full auto fire control group in my possession. Same with a pistol with a stock or an AR15 with a short barrel upper. Without a sear or SBR stamp, it's a gray area that could cause heartburn.
You took my quotes out of context. My first quote was related to the poster that said an m16 trigger, selector and carrier would make an ar15 full auto in 15 minutes. I was stating that it will not and you need the rest of the parts including the trip for it to work. The machining would be required for an original m16 sear because that poster was not talking about a registered trip at that point. The DIAS post came later. Are you saying you can buy an AR15 milled and drilled for an original m16 autosear?

My second quote said MOST ar15s won't accept the DIAS without machining and then you said the same thing by stating low shelf will and high shelf won't. You said the same thing I did in different words.
Sorry that I didn't understand which kind of "sear" you were referring to. My bad.

So what is so incorrect about my posts?
I've always heard that full auto trigger parts with a semi were considered constructive possession so could get you in trouble. The AR won't work without the machining for the sear so you could put those parts in but it's still a semi."
My understanding is that those parts can in fact convert a semi auto to full auto. It is true that the Tech Branch would certainly take notice of any full auto fire control parts in a semi auto. If a full auto selector with the other full auto fire control parts are in an unmodified semi auto AR receiver, even if the upper receiver has a semi auto carrier, the Tech Branch would consider that AR-15 an unregistered machinegun. If the selector is placed in the "AUTO" position, that will push the disconnector out of the way. Without the function of the disconnector, the hammer would follow the carrier back into battery. That could create a "slam fire" condition. Depending on the sensitivity of the primers, the next round could go off. If it did that would meet the definition of machinegun. This would not make reliable full auto function, but if the Tech Branch can make the gun "slam fire" once, is all it takes to be an unregistered machinegun.

The same could happen to a roller lock full auto trigger pack that was improperly converted for a semi auto application. To modify a full auto pack for semi auto use the section of the trigger frame which has the hole for the pin the "catch" (HK term for auto sear) rotates on, must be removed from the trigger frame. A new hole must be drilled through the frame to mount the trigger return spring in the pack. Another step is to relocate the trigger stop permanently in the pack.

The full auto stop allows the trigger to be pulled back far enough to eliminate the disconnector feature. So as with the AR with the full auto trigger, disconnector and selector, if the semi auto trigger group, without the semi auto trigger stop installed, and the selector is placed in the "AUTO" position, there is nothing to stop the hammer from following the carrier back into battery. This could cause a "slam fire" condition occur. The semi auto trigger stop doesn't let the trigger go back far enough to eliminate the disconnector feature. So both those modifications, plus the notch in the full auto hammer that would be used by the "catch" must be removed. All these modifications must be done to properly convert a full auto roller locked trigger pack for semi auto use.

My intent was not to insult you. My understanding of the AR system is with those full auto fire control parts in a semi auto AR, that semi would be considered a unregistered machinegun. To my knowledge you were posting misinformation. I have misunderstood different aspects before. We all make mistakes. I'm not saying that I'm an expert. I do own both systems and paid quite a bit of money for them. To set up both systems, I've spent quite a bit of time learning how those systems work. I would think very few users of this site are looking to illegally convert a semi gun to a machinegun. I'd think many more would get into trouble trying to convert a full auto pack to semi pack. All the modifications listed above must be done to avoid a "slam fire" condition, or to have a pack that would not be easily converted. YMMV.

Scott
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My understanding is that those parts can in fact convert a semi auto to full auto. It is true that the Tech Branch would certainly take notice of any full auto fire control parts in a semi auto. If a full auto selector with the other full auto fire control parts are in an unmodified semi auto AR receiver, even if the upper receiver has a semi auto carrier, the Tech Branch would consider that AR-15 an unregistered machinegun. If the selector is placed in the "AUTO" position, that will push the disconnector out of the way. Without the function of the disconnector, the hammer would follow the carrier back into battery. That could create a "slam fire" condition. Depending on the sensitivity of the primers, the next round could go off. If it did that would meet the definition of machinegun. This would not make reliable full auto function, but if the Tech Branch can make the gun "slam fire" once, is all it takes to be an unregistered machinegun.

The same could happen to a roller lock full auto trigger pack that was improperly converted for a semi auto application. To modify a full auto pack for semi auto use the section of the trigger frame which has the hole for the pin the "catch" (HK term for auto sear) rotates on, must be removed from the trigger frame. A new hole must be drilled through the frame to mount the trigger return spring in the pack. Another step is to relocate the trigger stop permanently in the pack.

The full auto stop allows the trigger to be pulled back far enough to eliminate the disconnector feature. So as with the AR with the full auto trigger, disconnector and selector, if the semi auto trigger group, without the semi auto trigger stop installed, and the selector is placed in the "AUTO" position, there is nothing to stop the hammer from following the carrier back into battery. This could cause a "slam fire" condition occur. The semi auto trigger stop doesn't let the trigger go back far enough to eliminate the disconnector feature. So both those modifications, plus the notch in the full auto hammer that would be used by the "catch" must be removed. All these modifications must be done to properly convert a full auto roller locked trigger pack for semi auto use.

My intent was not to insult you. My understanding of the AR system is with those full auto fire control parts in a semi auto AR, that semi would be considered a unregistered machinegun. To my knowledge you were posting misinformation. I have misunderstood different aspects before. We all make mistakes. I'm not saying that I'm an expert. I do own both systems and paid quite a bit of money for them. To set up both systems, I've spent quite a bit of time learning how those systems work. I would think very few users of this site are looking to illegally convert a semi gun to a machinegun. I'd think many more would get into trouble trying to convert a full auto pack to semi pack. All the modifications listed above must be done to avoid a "slam fire" condition, or to have a pack that would not be easily converted. YMMV.

Scott
Thank you for going into detail for what I did not feel like doing. :)
Thank you for going into detail for what I did not feel like doing. :)
You are welcome. Someone took the time to explain the finer points to me. So I feel obligated to take the time to explain the finer points to others. To me the whole point of this board is to pass on information. I've been around here quite a while and I'm still learning different aspects of roller locked guns. Just the other day there was a discussion about roller locked extractor springs. "G3K" posted that the standard rifle spring could not only be used in place of the standard 9mm extractor spring, he said it could also be used in place of the .40 caliber extractor spring. That would certainly cut down on stocking different extractor springs, at least for me. YMMV.

Scott
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