Thinking ahead a little bit just in case the rumors end up true. I know there is 922r issues to resolve if you SBR it, but would 922r come into play moving sear over to it?
Thinking ahead a little bit just in case the rumors end up true. I know there is 922r issues to resolve if you SBR it, but would 922r come into play moving sear over to it?
no it would not.
If they're now including the paddle-mag release as well as the tri-lug barrel perhaps the (FA) bolt block is gone as well. Too much positive mental attitude?
I'm expecting the block to be in place. I know were one is coming in soon for an HK employee. I'm hoping to get to see it in person.
If I pick up an SP5, it’ll be for the sole purpose of being a sear host.
I’m going to make the purchase of a sear a serious goal in 2021, depending on the election outcomes and political environment.
I’ve had my fill of satisfying 922r with my 3 HK/TBT builds, so an SP5 and SP5K will be solely sear hosts.
Any other rollerlocked guns I acquire will be exempt from 922r, so I’ll SBR a few.
So, it sounds like HK went further in putting in full auto carrier block than they did in the SP5K, doing basically what Zenith/MKE did, instead of a little nub like the SP5k. This is going to make it pretty difficult to use with a sear pack, unless someone can magic up a full auto carrier that can clear the block, but somehow have enough material to trigger a trip.
I've seen on Facebook that at least of a few big name MP5 smiths have already stated they won't be modding any SP5s to remove that block. My guess is everyone is gun shy over the ATF blocking up the Zenith modifications.
Here is what the ATF said, according to Zenith:
On May 17, 2019, Mr. Curtis sent BATFE’s formal reply, several excerpts from which are reprinted here (bold and underline are BATFE’s emphasis):
Previously, importers requested ATF allow a forward pin-hole in semiautomatic firearms, in order to give their firearms a more authentic appearance. These semiautomatic firearms continued to incorporate a “blocking shelf” in order to prevent the installation of an unmodified machinegun trigger pack. However, this “blocking shelf” was smaller than the original full shelf; therefore, a secondary blocking feature was required to prevent a semiautomatic firearm from being easily converted into a machinegun.
ATF has permitted semiautomatic receivers to include a forward pin-hole only if the receivers contain both:
A smaller blocking shelf, still preventing actual attachment of an unmodified machinegun trigger assembly; and
An internal blocking feature which prevents the installation of an unmodified machinegun bolt assembly.
Any HK-type receiver that contains a “blocking shelf” that is insufficient to prevent the installation a machinegun trigger assembly, constitutes a machinegun receiver, and will be classified as a “machinegun.”
Zenith semiautomatic firearms also incorporate a blocking bar in the rear of the receiver, which prevents the installation of an unmodified machinegun bolt carrier. This is consistent with other semiautomatic HK-type receivers, where the presence of a forward pin-hole and the smaller “blocking shelf” require a second blocking feature.
In your correspondence, you request permission to remove the secondary blocking feature in order to install unmodified machinegun bolt carriers. FTISB cannot approve this request because the Zenith Firearms without the necessary blocking features is a “machinegun” receiver.
That all being said, looking at what the ATF actually responded to Zenith about doing the mods, I'm not sure they really apply to the SP5.
I haven't seen an SP5 in the wild and the pictures I have seen aren't that great (though someone must have some detailed disassembly pictures out, or will soon). But looking at this picture from HK USA's website, it's very clear that the SP5 must have a full shelf. It doesn't have a second pin hole. If that's the case, the ATF message to Zenith shouldn't apply. They were hung up on the Zenith guns have double push pins and stating that the Zenith micro-shelf wasn't sufficient. But since the HK appears to have a full up shelf, like the older HKs and pretty much all the US built clones do, then I would think that means it would be okay to remove the carrier block.
That being said, I'm not sure most of 07/02s are going to want to put their licenses on the line in case the ATF decides to just make up more legislation out of thin air and declare removing the block is creating an unregistered machinegun.
Looks like a sear will be a no-go in the SP5.
Sear WILL be ok in SP5...Mark my text
Zenith letter doesn’t apply to SP5 or the SP5K. For starters it’s not a double push pin gun. Second, trigger pack is configured to semi and has no sear in it unlike the Zenith guns. If you read very carefully the Zenith guns also have an undersized sear block.
ATF letters, opinions, etc. don't really mean anything anyways.
What does the actual law read, or more specifically, define? Most of us are capable of thinking for ourselves, and apply our own interpretations of the law as it applies to what we are looking at.
Fundamentally and legally, you only have a MG if you get more than one round firing when you pull the trigger one time. After that, we are venturing into the land of policy, opinion, and the vast legal gray area that belongs to whoever has the money to either fight there or is the USG...in which case money is no object b/c the USG has an unlimited supply of money and lawyers thanks to your tax dollars.
Leaving aside who will actually do a modification, it seems clear the SP5 holds some good promise as a sear host provided:
1. It has a FULL SIZE SHELF indistinguishable from that on the 10,000s of legal HK-style guns out there (and NOT a smaller shelf like a Zenith). If the SP5 doesn't have a "standard" or full sized shelf you would need to permanently add one.
2. It has NO FRONT PUSH PIN HOLE the same as the 10,000s of legal HK-style guns out there (and NOT a more "cosmetically correct" hole like a Zenith). SP5 achieves the paddle mag release without a through-and-through hole like 1,000s of other HK-style guns out there now.
With both of these features in place, someone stupid enough to seek an illegal MG conversion will need to both defeat the shelf and the lack of a pin hole, i.e. a very deliberate action demonstrating clear ill intent (and not insignificant metal-working skills -- you can do it with a Dremel tool, but you have to want to do it).
The receiver block is reminiscent of the old "no F/A carriers" in the AR-15 platform in the sense it removes metal from the area it would interface with a F/A sear (or "catch" in HK lingo). Time and practice have removed the sensitivity of a "standard" carrier in an AR, and I believe the same practices and principles apply to the HK -- specifically running an unmodified carrier in either an AR or an HK is not a significant step in an illegal conversion as a standard carrier will only contribute to F/A fire if first you have an auto-sear (and proper F/A hammer)...and all focus should properly be on these parts rather than the rather benign carrier.
So if modified carriers are so insignificant why does the HK (and other imports) have them? Because the ATF is the gatekeeper on importing these pistols and has decided that as a matter of POLICY they will demand them for access to the U.S. market. It may not be a great thing for U.S. consumers (added cost, non-standard parts, etc.) but it is great thing for a USG bureaucrat to say they have gone "above and beyond" the requirements of the law and can never be reproached for their work by their superiors. U.S. consumers have no representative in the ATF approval process to protect their interests, and until the law changes you are gonna find increasingly funky modifications to imported guns. The good news is that there is still a measurable amount of freedom available to us once a gun is here in the U.S., and responsible firearm owners can modify their firearms consistent with the law.
Does this video help understand the details of the SP5:
When the video above was first posted I noticed it looks like HK put a wrap-around style semi shelf on the gun. However, it appears they then proceeded to drill a front push pin hole through the right side of the shelf and the receiver has what I presume to be push pin holes in both sides of the sheet metal receiver, but they stopping just short of drilling through the other side of the shelf.
HK then put a solid full size pin through the hole in the shelf and into the pushpin holes in the receiver (which is what the paddle mag rotates on) and the solid pin appears to have a little tack weld, similar to what keeps the standard push pin bushings from falling out of the receiver.
Pure speculation on my part, but the rear carrier block may be there because the receiver appears to have both front push pin holes in the sheet metal and one of those front push pin holes is exposed through the right side of the semi shelf.
Whether the regulatory agency in charge of issuing opinions on behalf of the federal government as to what constitutes a machinegun receiver would be of the opinion that an HK SP5 with its rear carrier block removed and the front shelf/exposed pin area left in its current OEM configuration rises to the level of a "machinegun receiver" is currently unknown.
The BATFE may eventually issue guidance that something as simple as a full circumferential weld around that solid front pin fully joining it to the shelf and receiver would suffice prior to removing the rear carrier block, or they may require even more aggressive modifications like removing the front pin supporting the paddle mag, welding up the push pin holes in the receiver sheet metal, and/or removing the current shelf with the hole in it and installing an original 9X style shelf.
Maybe we will all get lucky and the BATFE is good to remove the rear carrier block with no additional modifications to the gun.
That said, I personally wouldn't feel comfortable at this point removing the rear carrier block in the SP5 without some sort of guidance from the tech branch.... especially in light of the fact that its been 3 to 4 years since the SP5K was released and to the best of my knowledge nobody has received formal guidance on the legality of removing the little nub under the rear sight in the SP5K, none of the major HK smith I have talked to will remove it, and the SP5K has a more traditional semi-shelf without an exposed pin hole on the right side.
I am in no way saying somebody won't get a Zenith mod type of letter for the SP5 sometime in the future, but I wouldn't take a dremel to my SP5 rear carrier block tomorrow either.
Any chance someone's seen one in person and can elaborate on if it's sear ready? Or easily modifiable to be a host for a registered sear?
Here's some better pictures of the carrier block. As you can see, only the upper step of the block would need to be milled off for a full auto carrier to clear it. That would be super easy to do with a Dremel, although, I'm not advocating it's okay to do that, but I do find it interesting that HK made that little step exactly where the cut would need to be made for full auto carrier clearance.
As soon as the receiver is modified, machine gun. If you modified the bolt, sear host. My 2 cents. That is why the block is on the bottom now vs. SP5k.
No Sp5 sear host. Unless someone can mod a bolt to clear that....
But hey, maybe some will sell their 94's a cheap prices now.
Also, I imagine this is the same as the elites rerelease, spares laying around mobilized for cash. I doubt there will be more than 500 on this run.
Well it is going to be more difficult than simply shaving the top off the bolt to clear the last top nubbin that is for sure...
It looks as if HK put special effort into making certain that the new SP5 will not be able to be a sear host. A new video on youtube goes into a disassembly of the SP5 and at about the 2:00 mark the video goes into comparing a semi action bolt carrier to a full auto bolt carrier. The semi auto bolt carrier has metal milled from the bottom so that it won't trip the trip lever on a full auto pistol. Other than that the bolt carriers are identical.
I'm not saying it can't be done somehow, but HK definitely chose to make it next to impossible to host a sear in the SP5.
Here's a link to the video https://www.youtube.com/watch?v=0jxSpgNfCV0, and a picture below showing the differences between the semi auto and full auto bolt carrier. The full auto bolt carrier is on the right.
Sent from my iPhone using Tapatalk Pro
The same could be said for cutting the shelf off a 94, are there any clones being built without the shelf? No. Machine gun. So I guess if you are suggesting you could cut the lower nubbin off and add a semi shelf to the magwel then yes I guess you could probably do that, but why would you do that? Modifying the receiver in a manner they could interpret as easily convertible sounds dangerous to me even if it only shoots 1 shot per trigger pull, the bolt is what needs to be modified in my humble opinion.
The primary difference from my vantage point is that US made clones don't have push pin holes in the receiver and nor is one of those push pin holes exposed on the right side of the shelf. Looking at the HKPro members detailed video I am not sure if the solid pin through the shelf and receiver on the SP5 is even welded in, it looks like HK put the solid front push pin in and then just maybe peened/staked part of the shelf to keep it from falling out. Red arrow pointing to what appears to be a small stake mark vs. a weld.
In terms of using an SP5 as a sear host, I was looking at one of my MP5s this evening and how the sear trip lever interacts with the carrier. The SP5 rear carrier block based on the pictures in this thread appears to be about half of the width of the trip area on a full auto carrier. Unfortunately, that carrier block is also right in line with where the full auto trip lever is in the trigger pack.
So if you were to mill away part of the trip lever engagement ramp on a MP5 full auto carrier enough to clear the carrier block in an SP5, it looks like you would be left with about ~50% of the sear trip ledge on the MP5 carrier in order to clear the block. Unfortunately that is also the critical area on the MP5 carrier where the sear trip lever in the pack hits the trip ramp on the carrier.
However, if you were to thicken/widen the sear trip lever in the pack on the left side.... say by cutting the triangular portion off the end of a spare sear trip lever, and welding or soldering that cut piece of trip lever to the left side of the existing sear trip lever in the pack (essentially doubling the sear trip lever area thickness on the left side), it looks like there may be enough of the trip ramp left on a MP5 full auto carrier to engage a modded/thickened sear trip lever, even after removing part of the sear trip ledge on the carrier to allow it to clear the carrier block in the receiver .
I don't have a SP5 in front of me to measure the thickness of the carrier block and exactly how much of a full auto carrier trip ramp needs to be milled away to clear it.
It looks like there could be a cottage industry of SP5 "sear ready" thickened width sear trip levers and corresponding SP5 "sear ready" full auto carriers with part of their full auto trip ledge milled away in order to clear the block in the receiver, but leaving enough material to engage a thickened sear trip lever so that it will all work.
That way the receiver could stay "as is" without modification but you would need a modified MP5 carrier to clear the SP5 block as well as a and modded sear trip arm that could engage the reduced in size trip ramp on the modded carrier.
We would need somebody with a SP5 and full auto carrier to measure how much of a full auto carrier trip ramp needs to be milled away to bypass the block (and ultimately how much of the ramp is left) to confirm if this potential sear host workaround is a viable workaround.
Removing the block in an SP5 seems akin to drilling a 3rd pin hole in an AR lower.
With that being said, you all are politely Internet fighting with each other over unknowns. The SP5 will be a great sear host.
"So if you were to mill away part of the trip lever engagement ramp on a MP5 full auto carrier enough to clear the carrier block in an SP5, it looks like you would be left with about ~50% of the sear trip ledge on the MP5 carrier in order to clear the block. Unfortunately that is also the critical area on the MP5 carrier where the sear trip lever in the pack hits the trip ramp on the carrier.
However, if you were to thicken/widen the sear trip lever in the pack on the left side.... say by cutting the triangular portion off the end of a spare sear trip lever, and welding or soldering that cut piece of trip lever to the left side of the existing sear trip lever in the pack (essentially doubling the sear trip lever area thickness on the left side), it looks like there may be enough of the trip ramp left on a MP5 full auto carrier to engage a modded/thickened sear trip lever, even after removing part of the sear trip ledge on the carrier to allow it to clear the carrier block in the receiver "
I mean I dont know if it will work yet, possibly. But I do know this is the path, if you cut the nubbin off the reciever, machine gun.
Unfortunately this is it, no mods to the receiver, period, or machine gun.
Back of the bolt may catch when rollers in and...bad news. It late.
All said I would still prefer a 94 for host.
I agree I would still prefer a 94 as a sear host all things considered.
However if you look at the bottom of the MP5 bolt the cut on the bolt is just as wide as the sear trip lever slot on the carrier. So as long as a modified trip fit through the the relief slot carrier forward of the trip ramp you would be fine on the bolt as well as the relief slot on the underside of the bolt is identical in width.
In the attached pic you can see the mark in the oil/grease where the trip is currently hitting the trip ramp on the carrier and the marked area in red to the left (or top on the photo in the current orientation) that could be utilized to engage a modded lever that was either offset or thickened.
The big question is can you remove the area below the red mark, (roughly where the trip is currently hitting and to the right), and still have it clear the carrier block in the SP5 receiver or does basically the entire trip area have to be removed to clear the block in the receiver.
Yes, looks possible, and you are on the right path, but I am still not sure about that corner on the backside of the bolt, might hang on modified lever. If it does, bad. Lots of mods to get it running, SP5 destined to be SBR only, as the fine folks at HK and ATF desire. In fact I bet next run of SP5k have same repositioning of nubbin to achieve same outcome. And these are the last, it seems our friends at Orbendorf are out of parts, what up with that rear sight, retooling for actual production will take serious time and money for an outdated platform. Honestly I am surprised that barrel made it through the gauntlet as well...perhaps additional reason to make it sear incompatible, just random thoughts late at night...
Removing the SP5 block is like removing the old Colt autosear blocks (that projected out of the top of the lower receiver) on AR rifles in the 80s. Both blocks require the use of a modified carrier (the infamous "C" carrier in the case of the Colt) that has material removed to avoid contact with an autosear (should one be present). We don't have sear blocks in ARs any more, and I don't think you need one for a HK gun...other than to appease ATF bureaucrats who get to use ATF policy (not exclusively the law) to determine what is importable into the US.
Remember, guns just have to meet the standard of not being "easily convertible" they don't have to be impossible to illegally modify. That is why we now use standard carriers in our ARs, and many young shooters have (fortunatly) never seen an AR sear block or a C carrier. You can mill off a Colt sear block without a problem vis a vis the ATF, so removing blocks isn't necessarily seen as a step toward conversion in that case.
Seeing the general acceptance of the sear block on the SP5, I wonder if we are going to see Colt-style sear blocks on new MR rifles coming into the U.S.?
The carrier block is exactly in line where the trip lever would contact the carrier ramp, so I don't thing that would work, unfortunately. You almost need to have some sort of removable ramp that can be screwed in place on the carrier once it's inserted into the receiver.
That would bring up another question... would a "screwed-in trip ramp" hit the block as the carrier recoiled? Anyone have an opinion on that...does the carrier travel that far back during recoil?
That leaves you with what appears to be at least 50% of the ramp on the carrier left. At that point you just need a new updated trip lever with a slightly widened engagement surface to engage that remaining portion of the ramp on the MP5 full auto carrier.
The angle of this picture isn't ideal, what we need to see is the same pic/mockup of a MP5 carrier being inserted into an SP5 but looking directly down into the receiver to see the exact overlap area on the MP5 carrier that has to be removed.
LRM-I think you got it, but who is going to want to attach a removable after inserted? Way past desirable smithing for end result, get a clone or a 94. Probably better to leave the few of these that come in NIB and not go through all of the trouble for a "blaster", just my 2 cents.
Enjoy the sunset and be thankful a few more made it in, to all that pick one up!