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

4895 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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modifying the pack for s/a is really pretty easy. You need to buy a new sear spring and spacer but everything else can be done in a few minutes with a dremmel and cutoff disk. Check out the diy postings on weaponsguild.com. very helpful. may even be something here posted as a how-to.

in a nutshell: cut the front corner off so the auto sear pin hole is gone. drill a new sear spring hole in the remaining nub of the trigger pack (just look at some side by side pics of f/a and s/a packs and you'll see what i'm talking about). throw auto parts away, and grind the f/a stop off of the hammer. the only semi-difficult part is just knowing how to disassemble and reassemble the trigger pack. good pics help with that.
You have most of the pack modifications correct, but you are missing a very important detail. A semi auto trigger stop must be permanently added to the pack. If not, if the selector is placed in the "AUTO" position, the disconnector will be out of the way if the trigger is pulled back to the full auto trigger stop. So the hammer can follow the carrier back into battery. While it might be difficult to make happen, depending on the sensitivity of the primer, if the next round goes off, the gun has now met the BATF&E definition of "machinegun". It would only have to happen once to be eligible for prosecution. My understanding is that possession of an unregistered machinegun could carry a fine of up to $10,000 and/or ten years in Federal prison.

For those interested in using a full auto parts set to build a semi auto firearm, I would highly recommend the The Complete Reference on the Legal NFA Conversion of HK Firearms so you understand what can and can not be done to receivers and parts. There is some great articles in "The World Of HK". The Tech Branch has come up with the methods that are allowed and not allowed. While removing the standard "catch" (HK term for auto sear) hole from the trigger frame is required, removal of the "catch", trip lever, and round off the notch in the hammer that would be held by the catch are required for full auto to semi auto trigger pack conversion. But permanently installing a semi auto trigger stop is also required. Good luck with your build or selling your parts set.

Scott
 

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A semi auto weapon that will accept a full auto pack is not illegal. If you ALSO have a full auto pack IN YOUR possession makes everything ILLEGAL, and you go to jail.
Could you please give more detail as to how a "semi auto weapon that will accept a full auto pack is not illegal"? A semi auto roller locked receiver has a "shelf" attached to the receiver where the front push pin of a full auto trigger group would be. To be able to install an unmodified full auto pack in a semi auto receiver, the "shelf" of the semi auto receiver would not allow the unmodified full auto pack to be installed into the clipped hosing and put together. Removal of the "shelf" to allow use of an unmodified full auto housing would convert the semi auto receiver to a full auto possible receiver. So a semi auto receiver modified in this way would no longer be considered a semi auto receiver. So how could a "semi auto weapon that will accept a full auto pack" be a legal semi auto firearm without the "shelf"?

My understanding is a standard semi auto receiver with the "shelf" can not accept an unmodified full auto trigger pack. That is why it is legal to have a full auto parts set and a semi auto receiver. The full auto parts can not function with a semi auto receiver. The modifications required for full auto parts to function automatically with a semi auto receiver have already been written out by the Technology Branch as being illegal modifications. Preforming those modifications without NFA approval would be a felony. At least that is my understanding. YMMV.

Scott
 

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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.

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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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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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