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View Poll Results: Would Replacing The Factory M10 Sear With A Tenko Specific Sear Be A Deal Breaker?

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  • Yes

    14 18.92%
  • No

    45 60.81%
  • Depending Upon How Difficult It Is To Change The Sear

    17 22.97%
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Thread: Tenko 10-16 Function Questionnaire

  1. #1
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    Talking Tenko 10-16 Function Questionnaire

    We are finalizing our design for the Tenko 10-16 adapter for the M10 family of RR machineguns. For those of you unfamiliar with the Tenko, it is an adapter as opposed an "upper ". The Tenko adapter will give similar functionality to that of a M16 registered receiver. So a standard AR-15/M16 upper receiver in whatever caliber that can be fed with a magazine that will fit into a standard AR-15/M16 magwell. We are planning to submit two different versions. One will be based on the standard closed bolt upper receiver. We plan to submit using a CMMG rotary delayed blowback 9mm upper. The other submission will be based on the Colt LMG open bolt mechanism. This system uses standard upper receivers but the bolt (9mm blowback) or carrier must be modified on the bottom with a notch that hooks into a notch at the top of the hammer. We plan to submit the open bolt example with a modified Colt blowback 9mm upper. Both submissions will include a 9mm incert in a Pmag.

    Our original design was activated by the standard M10 sear. So it was quick and easy to go from factory style upper to Tenko adapter and back. Sadly we have had to make our own replacement sear for use with the Tenko. We have three interlocks that will be unlocked by installation into a M10 registered receiver. But without the M10, these locks would need to be defeated in order to get the Tenko adapter to fire with an upper.

    So what I am looking for is some feedback. Would having to change the sear from factory style system to Tenko adapter system, be a deal breaker for you? For those that aren't familiar, the fire control pin retaining spring must be lifted , the selector pins is pushed to the right. The factory sear and semi auto trip are removed from selector shaft and the selector shaft is removed. The fire control pin retainer spring is lifted so the Eliminator pin slides under the spring from left to right, is slid through the Tenko specific sear, and into the right side sear pin hole in the frame.

    Scott
    Manager A&S Conversions L.L.C.

  2. #2
    Registered User Deerhurst's Avatar
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    Can I change it in the field? If not, deal breaker.

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    Don't know that I would change it back to the original configuration once it is in place. Tons of options and calibers out there to play with so not a problem for me. Thank you and on the waiting list

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    Will conventional uppers work with the new sear?

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    I think caliber conversion (and especially adding rifle caliber functionality to the m10) outweighs quick change modularity by a long shot. Replacing the sear to change configuration back to the original upper would not be a deal breaker for me at all.

    Are you concerned that a non-firearm determination could come with the caveat that the determination only applies to the specific configuration submitted? ie, the Tenko adapter + 9mm CMMG is not a firearm, but Tenko + Alexander Arms .50 Beowulf upper would need its own submission? Not trying to be a downer, just curious after the nonsense they pulled on your last submission.

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    Honest answer, depends what Lage gets to market with, price point on each, etc. The Tenko seems more versatile, in terms of different AR uppers, especially if I also shell out for one of the belt-fed AR uppers, but part of why I got the M-10 is that I (foolishly) thought that having already OK’d the M11-15, ATF would have no reason to hold up an M-10 version of the same damn thing. Ultimately, though, it’s probably more a matter of what order I buy things in than really which things I buy, because I’m going to want to try everything. May wind up reselling some of it, but probably not unless I get married or run out of Scotch money.

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    Registered User Deerhurst's Avatar
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    I think the last 3 posts have very valid points.

    I was under the assumption that the specialty sear would have to be replaced to go back to an other upper. I love my Max10/31 and do not have any interest in building an AR upper in 9mm or really any other pistol cartridge (except my existing 7.62x25 upper). For me the Tenko would be a rifle caliber or oddball caliber thing only. Magwell adapters are a pain in the butt sometimes. I'm still looking for the Colt 9mm adapter a buddy has somewhere in his shop. What happens if the scum says the Tenko (an accessory) is a firearm if it doesn't have a pistol caliber upper on it? We know that would be BS but NFA folk tend to like to not toe the line.

    I also agree that if the Ultimac or the Lage hit the market first it would be hard not to buy one and deplete the funds set aside forac stuff. By the sound of it those would just require a bolt and barrel change to do other calibers. While it's not something you'll do in the field it isn't difficult.

    I love swapping around uppers all the time. I do the same with ARs, a couple lowers and a bunch of uppers in different calibers and configurations.

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    Scott, IF possible, a picture please. Especially for us non technical/non engineer simple types; "a picture is worth a thousand words" concept. Thank you Sir!

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    As far as changing the sear at the range, that would be up to each individual. I'll see if I can't post a video of how to change the sear. Certainly if the owner wants semi auto function of the factory style upper, then replacing the Eliminator pin with the original selector pin and semi auto trip would add a slight amount of complexity. My personal opinion is that the sear swap would be something that I would do at the range, but I don't speak for every.

    As far as what caliber the ATF could approve or deny, I don't have a crystal ball. So I have no idea what kind of stuff they will try to say. They were quite adamant that they got the second submission to fire multiple rounds, so the aluminum version of the Tenko adapter, was in their eyes, is a machinegun. Fighting them over what is and is not a firearm is a non starter. The courts would almost certainly side with the opinion of the Technology Branch. The ATF can't tell us what to do, in a determination. They can only say what they didn't like. So we are following their play book. The design is or is not a firearm or machinegun. By design, the adapter has none of the features of a firearm. The ATF got the adapter to fire more than one round so the adapter could be considered a collection of parts including an AR upper receiver.

    What the outcome of anyone else's product, I have no idea. But I wish everyone else luck with their submissions. How things will go with our third and fourth submissions, I don't know. The open bolt mechanism has a notch on the bottom side of the bolt (9mm blowback) or carrier. Once the notch is made the same upper can be used in both open and closed bolt mechanisms. The only downside for an open bolt modified carrier would be if used with a Colt semi auto hammer with the notch at the top of the hammer.

    Scott
    Manager A&S Conversions L.L.C.

    For those that are interested https://m.youtube.com/watch?v=skPApyrdI2s is a video that Sam made installing the fire control of a M10. What you would need to do with changing the sear starts at 2:30 in the video.
    Last edited by A&S Conversions; 05-16-2021 at 08:56 AM. Reason: Add fire control installation video link.

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    Second that question, will factory uppers work with your new sear? I would hope its possible somehow.

    I have a m11/9, and switch between uppers on most range days, really love that versatility. My m10/45 I'd imagine I still want to shoot my Lage upper, and then pop on an AR upper with your device. It may be na´ve, but one thing I'm wanting to do is reliably shoot 22LR in an AR upper with a CMMG kit and mags that won't be as finicky. I'm also in that same boat, anxiously awaiting the ultimac (so plan to use that as well on the m10/45).

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    I will buy the first upper/conversion that comes to market. After that I will consider what comes to market and it’s competitors by what each brings to the table. The sear would be a consideration if I already have a rifle caliber upper.

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    Freudian slip in the thread title?

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    Scott, does the sear work with other uppers? Or would it have to be changed to shoot the stock upper or a Lage for instance

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    Quote Originally Posted by Gaujo View Post
    Scott, does the sear work with other uppers? Or would it have to be changed to shoot the stock upper or a Lage for instance
    Yes the sear would need to be changed to the supplied sear for Tenko use and back to the factory sear for factory style upper use. The latest Tenko designed sear would only work with the Tenko adapter.

    Scott
    Manager A&S Conversions L.L.C.

    ETA In the future it might he possible to make a dual use sear. Our R&D budget is very limited right now. I don't want to bring a product that is not 100% to market. One of our submissions will be a dual use sear design. But without the testing, required as that sear would need extensive testing of both Tenko functionality and standard functionality. I just don't have the resources right now to do both.
    Last edited by A&S Conversions; 05-16-2021 at 05:42 PM.

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    For me the bigger deal breaker is not having an positive determination letter with a rifle caliber upper in either open /closed bolt configuration. You have already said in another post "the Technology Branch said in their determination that they didn't like that the Tenko was closed bolt and rifle caliber". I don't have a need for an expensive adapter that allows me to shoot 9mm out of a gun I can already do that with.

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    Quote Originally Posted by mak91 View Post
    For me the bigger deal breaker is not having an positive determination letter with a rifle caliber upper in either open /closed bolt configuration. You have already said in another post "the Technology Branch said in their determination that they didn't like that the Tenko was closed bolt and rifle caliber". I don't have a need for an expensive adapter that allows me to shoot 9mm out of a gun I can already do that with.
    We will see what they do with the next two submissions. The basic mechanism we will be sending in the next two submissions is the same mechanism as the first submission. So we start on the bottom level and work our way up. To change calibers is a simple parts swap of unregulated parts. We have not even submitted yet. Once we get a response to the submissions we will determine our next step.

    Scott
    Manager A&S Conversions L.L.C.

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    We are all very fortunate to have great folks like you, Richard, Sam, and few others who are relentless innovators contending with a unconstitutional corrupt 2A stealing false government agency.

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    Doesn’t matter to me as once I could use AR uppers and Pmags the Mac uppers would be worthless to me.

  19. #19
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    With plans of making a universal sear I'm still interested!

  20. #20
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    To be clear, to change the sear, lift the fire control spring out of the notch in the sear pin, push the pin to the left and pull it out of the sear, pull the sear spring out and place it into the sear going in, place the sear with the spring into the M10 sliding the sear pin through the hole with the disconnector hook on top of the notch in the sear for the hook to catch, and slide the retaining spring back into the notch to lock the pin into place. The process should take less than a minute and requires no tools.

    With what is going on at the ATF, I don't think they will just approve the submissions. I am expecting a fight. What exactly will be the fight, I don't know. As with the M16 and other machineguns, as long as there is no permanent modification to the receiver (the regulated part), which our product does not require, changing parts is not regulated. In talking with a NFA specific lawyer, there is no legal way for the ATF to specify caliber. Either the mechanism is or is not a NFA regulated item, or the item is or is not a firearm.

    For those that are interested, this is the proposed change to https://www.atf.gov/rules-and-regula...ceiver/summary firearm frame or receiver. Specifically:

    "Under the proposed rule, a “frame or receiver” is any externally visible housing or holding structure for one or more fire control components. A “fire control component” is one necessary for the firearm to initiate, complete, or continue the firing sequence, including, but not limited to, any of the following: hammer, bolt, bolt carrier, breechblock, cylinder, trigger mechanism, firing pin, striker, or slide rails.

    Any firearm part falling within the new definition that is identified with a serial number must be presumed, absent an official determination by ATF or other reliable evidence to the contrary, to be a frame or receiver.

    More than one externally visible part may house or hold a fire control component on a particular firearm, such as with a split or modular frame or receiver. Under these circumstances, ATF may determine whether a specific part or parts of the weapon is the frame or receiver, which may include an internal frame or chassis at least partially exposed to the exterior to allow identification.

    The proposed rule maintains current classifications and marking requirements of firearm frames or receivers, except that licensed manufacturers and importers must mark on new designs or configurations either: their name (or recognized abbreviation), and city and state (or recognized abbreviation) where they maintain their place of business; or their name (or recognized abbreviation) and their abbreviated FFL number, on each part defined as a frame or receiver, along with the serial number.

    The proposed rule includes examples of types and models firearms and identifies the frame or receiver. Most examples also include an illustration identifying the frame or receiver. It also explains when a partially complete, disassembled, or inoperable frame or receiver is considered a “frame or receiver”, and explains that a destroyed frame or receiver is not considered a “frame or receiver”."

    Our submission does not fit this new definition of firearm frame or receiver. As designed, the fire control is mounted into the M10 lower. The other listed fire control parts are inside the AR upper. The adapter doesn't hold any of the listed fire control components. The ATF has already determined that the AR lower is the regulated part, so the AR upper is not a regulated part. They have also determined that the M10 lower is the regulated part, which is where the other regulated parts must be.

    Again, I don't have a crystal ball. If the proposed changes are put through linked to above, that would certainly make innovation so much more difficult, if not impossible to achieve. ATF basically wants to make anything, that they have not made a determination on, a regulated part. A regulated part (firearm frame or receiver) can not be used with a transferable machinegun. That is one too many firearms, firing automatically. I am sure that the ATF will try to argue that the Tenko adapter somehow fits into this new definition. Very dark times ahead.

    Scott
    Manager A&S Conversions L.L.C.

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