EXCLUSIVE: PATENT ATTORNEY Explains The Complex Mossberg Patent Situation

A drop in Timney Trigger. Timney was sued by Mossberg for infringing on their patents.

[ Steve says: This guest post was written by a practicing patent attorney with no connection whatsoever to the Mossberg AR-15 trigger patent lawsuits. ]

With the whole Mossberg drop-in trigger stories of the last week I have been asked to give a brief overview of what a patent is, and how it works. Since this is an extremely complex topic and a whole specialized profession has been built around, I can’t describe every facet, but I hope to be able to give sufficient detail that readers will be able to look at patent cases more critically and in a more informed manner.

So what is a patent?

In short, it’s a limited monopoly right to prevent others from exploiting an invention, for up to 20 years from filing the application. There are some small exceptions to this, but don’t worry about them. It is a piece of property that can be bought, sold, licensed and so on. If it couldn’t be, it would have no value to someone who doesn’t want to, or can’t, produce themselves.

It’s also an exchange. In order to be granted the patent, you have to disclose to the world how your invention works. This enables others to find out about it and build on it. So we exchange information for a time-limited monopoly right.

What is a patent not?

It’s not an automatic right to exploit the invention yourself, since you can be within someone else’s broader patent. Example (please suspend disbelief): I’ve just invented the chocolate chip cookie, and I’ve been granted a patent to it. I can’t sell chocolate chip cookies, however, if there’s someone else who holds a similar patent protecting cookies in general, but not ever mentioning chocolate chips (he hadn’t thought it possible, thinking that they’d just melt into mush).

So I’m stuck. I’m blocked. But, chocolate chip cookies are better than just plain cookies. I can prevent Mr. Cookie from selling chocolate chip cookies, just as he can prevent me from selling any cookies at all. But, unless Mr. Cookie is totally unreasonable, he’ll want to be able to sell the improved cookies, so we’ll trade: he’ll let me produce chocolate chip cookies, if I let him produce them too. A “cross-license”, which is a win all around! Then the marketing guys can make a fortune on ad campaigns….. But I digress.

It’s not a right that’s unlimited in time. Once it expires, it’s gone and anyone can use the invention for profit.

What does a patent have to be?

To be valid, a patent has to claim something that is new, and is not obvious, and describe it well enough that someone else can replicate it. Note that it is what is claimed that counts – it is not some random statement in the description, or some vague concept, but the independent claims. These are claims that are not “according to” an earlier claim. “Dependent claims” refer to other claims and add more features and serve as more specific, narrower, claims as fallback positions in examination or validity proceedings, and have some other minor functions. Don’t worry about them – if you’re not infringing an independent claim, you’re not infringing a dependent one either, by definition.

So, when you’re looking at a patent, start with the claims first, even though they’re at the end. Because it’s these that define what is protected.

Now, often the claims are super dry, crazily abstract and hard to follow. Then you need the description and the figures to work out what’s going on.

“New” means “not literally disclosed before”. This is fairly simple – does one variant in a document, or a product, disclose all of the features of a claim? If yes, then it’s not new. If no, then it is and we move on to obviousness.

Obviousness, or “inventive step”, is trickier, more subjective, and each country determines it a bit differently. In brief and over-simplifying somewhat, in the US, if several documents disclose all the features of a claim and the skilled artisan (who is not an inventor) would put them together to arrive at the claim, then it’s obvious.

Now, let’s put this into the context of the Mossberg patent, US 7,293,385 as granted, just taking the simplest and broadest independent claim, number 1. All the information below is in the public domain, downloadable from the USPTO Public PAIR service.
Now what a patent attorney does in this situation is split the claim down into its original features, and compare them with the prior art, often in the form of a table. For reasons of space, I’ll just reproduce the claim, with the features known in e.g. a random pinned-in trigger pack in italics:

  1. A trigger group module for a firearm, the firearm including a receiver that defines a trigger group receiving area between a first receiver side wall and a second receiver side wall, the trigger group module including:
    (a) a module housing adapted to be inserted to an operating position in the trigger group receiving area, the module housing having a lower extremity that is located above a lowermost edge of the first receiver side wall and a lowermost edge of the second receiver side wall when the module housing is in the operating position;
    (b) a number of trigger group components mounted within the module housing;

    (c) a first pin receiver positioned in the module housing so as to align with first pin receptacle openings of the firearm when the module housing is in the operating position, the first pin receptacle openings defining pin support surfaces formed in the first receiver side wall and the second receiver side wall; and
    (d) a first module pin mounted in the first pin receiver on which one of the trigger group components is supported in the module housing,
    the first module pin including an opening that aligns with the first pin receptacle openings of the firearm when the module housing is in the operating position.

Firstly, note how if we take the HK trigger pack, or the Petter-type of the SIG P210, don’t even have all the features in italics, since they’re not pinned in, so don’t have feature (c) at all.

Now, the features in bold are the key to this patent. What this claims, in plain English, is the hollow pin arrangement which aligns with the existing openings in the receiver and also supports a trigger group component (such as the hammer, for instance, although this is not specified). In the first round of examination, nobody presented a document showing this feature, and it seems to be a clever way to simplify mounting using existing holes, to save space in the module since no extra pin pass-throughs are needed, and any number of things that can be thought up by a half-competent patent attorney.

However, if someone turned up a document showing such hollow pass-through pins, then Mossberg would be in a heap of bother.

A first re-examination (control number 90013200 at the USPTO if anyone is interested), presented this document (belonging to Jewell):

Screen Shot 2016-06-02 at 2.15.52 PM

Hmmm. Part 30 at first glance looks suspiciously like a hollow pin arrangement like in the claim. But the Examiner disagreed, stating that the document “shows a mounting pin 30, but the pin is solid and has no opening. The sleeve that the pin (30) passes through cannot meet the claim limitations of the pin, as it is not supported by pin support surfaces formed in the receiver side walls. None of the other cited references provide a teaching of a pin having an opening which aligns with openings in the firearm”.


This is where it gets interesting (and complicated). In view of the complexity of the case, I won’t go into details.


But in essence, the novelty of the independent claims is not in question, contrary to some very strongly-held beliefs in forum comments. Sorry, guys. If you know differently and can provide concrete evidence, then the USPTO would like to know. So write them.

The examiner relies on the combination of the Jewell document with both US 3,707,796  showing a hollow pin and US 5,904,132 showing the position of a module in a receiver to assert that the McCormick patent is obvious, through a somewhat complex reasoning. However, this relies on the Examiner considering that the cavity in the stock 16 of Jewell is in fact part of the “receiver”… (surely that depends on what the meaning of “is” is…) And combining three documents, which is already getting onto shaky ground.

In case anyone spots it, there’s also a document mentioned in the proceedings which does show a hollow pin arrangement (US 7,421,937), but this is “sworn behind” and is disqualified as prior art (technical issues relating to dates and ownership of the invention. Don’t worry, just accept it’s out).

Anyway, without going into gory details, the job of Mossberg’s patent attorneys now is to try to get around the Examiner’s arguments while still covering the infringing products. They’ve been amending the claims, and are now pushing independent claims limited to modules containing two of these hollow-pin arrangements (the latest version at the time of publication was filed on April 21, 2016). A subsequent office action is rather negative though.

We’ll see how this develops – I don’t want to call the final result one way or the other at this point, since the case is complex. And once the re-examination is over, there are appeals and so on, so it could be a long while before it’s settled.

Steve Johnson

Founder and Dictator-In-Chief of TFB. A passionate gun owner, a shooting enthusiast and totally tacti-uncool. Favorite first date location: any gun range. Steve can be contacted here.


  • m-cameron

    steve….do you honestly have nothing else to write about?……..no one cares about the mossberg patent……you seem to be the only one.

    for the love of god, drop it and write about something people actually care about

    • Mike N.

      Au contraire. I find this very interesting.

    • Lemdarel

      I care, and I’m interested in reading about it. Keep up the good work Steve!

    • Yeah, uh, nah bruh. People care.

    • lowell houser

      I find this very interesting, because the more people are exposed to this sort of info, the more they realize what a bad idea patents and trademarks are and how they destroy competition and consumer choice, as in this case, years after the fact. Patents are after all, government granted monopolies.

      • Mike Burns

        I guess you don’t want new drugs and innovative products to be developed then?

        Say you invent a new product. You invest your life savings and several years in developing it and bringing it to market. Two months after your product is announced, suddenly BigCo floods the market with copies at a fraction of the price that you can sell yours at. Cos they’ve not had to pay for R&D, they’ve just reverse-engineered yours. Reverse-engineering costs a fraction of developing from scratch. Anyone can thus benefit from your invention and rip you off.

        Say you’re a pharma company. You’re not going to sink 4bn dollars and 10 years into a new drug if it’ll be reverse-engineered within 6 months of it coming on the market. So no new innovative drugs.

        The patent system is certainly not perfect, but spend a couple of minutes looking at what a patent-free world would look like – and it looks like those two examples above. The system does actually for the most part do what it says on the tin.

      • Bradley

        Hell yes!

    • 11b

      If you don’t care why are you reading an article about it? You have to physically click the link to read this article, it wasn’t an accident. Do you honestly have nothing else to complain about than an article that affects you in no way at all?

    • Smedley54

      Consider it educational. You may have a million dollar idea some day, and you’ll want to protect it long enough to get the kids through college.

    • Cymond

      Yeah, that’s why the other articles in the series have so few comments, obviously no one cares.

      Hey, wait a second …

    • Riley

      I find it very interesting. I hope someone is able to beat this patent early. The more cases they win against the small fish the more of a precedent they will have against the bigger fish that have the money to really fight it.

      If the patent is heldup, it could cause the price of drop-in triggers to be even more expensive than they already are.

      It will be interesting to see how things develop. I can see people swearing off Mossberg depending on how things go.

      • Bill

        I wouldn’t swear off Mossberg for protecting what they paid for, and they aren’t that large of a company to begin with. They have interests to protect.

    • So for your first comment on TFB this is what you say! You realize you are very much in the minority with that opinion.

      • politicsbyothermeans

        Unfortunately, it’s not his first. He seems to base his understanding of patents on the same thing he bases his “knowledge” of firearms and tactics, playing COD in his mom’s basement.

    • Then don’t read it——

    • DW

      I donno, looking through your comments you seem at little… triggered.


      • KestrelBike

        m-cameron’s post worth it just for DW’s response. hahahah

    • Chazz Matthews

      Says the Mossberg CEO.

  • Daniel

    I just hope CMC goes out of business because they believe in Jesus!

  • aka_mythos

    They keep calling it a hollow pin, but it seems like a pass through bushing. A necessity of geometric compatibility. In these instances of drop in trigger groups those holes have to be there to accommodate pins. These manufacturers didn’t design the receivers or the pins, thus its geometric necessity. Can any trigger group be assembled into the rifles in question without a void or absence of material to allow pins to pass through? -Not really.

    • Smedley54

      Just remember that some attorneys live to dispute the meaning of “is” and all becomes clear. Relevance is irrelevant, they just need a loophole, any loophole, to dive through.

    • Stan Darsh

      As I’ve said in an earlier post: Right now it seems unlikely mossberg will win and are trying to get royalty contracts in place with these small companies before the mossberg drop-in trigger patent becomes officially invalidated. There are numerous examples of prior art from the Taiwanese T86 to the 10/22 Exotic Weapon System and especially the Ithaca Gun Company’s US4103586-A patent, which includes “hollow bushings through which the receiver pins pass, and FCG parts pivot on those bushings” that prove the mossberg patent isn’t valid because the invention already existed, and/or it was not novel and didn’t teach anything.

      On top of that, if you look at the ex parte re-examination communication (USPTO Public Pair search section: Reexamination Control Number 90013341) It shows mossberg’s patent claims 1,2,4 and 10 have been officially canceled with claims 3,5,6,7,8,9,11,12,13,14 and 15 are pending a final ruling but are, at current, rejected.

  • Lets use this one instead

    • jng1226

      Haha, thanks Phil. Still a bit harsh but gets the point across a little “nicer”

  • fleetwrench

    Remington 870 1100 1187 modular trigger group held by two pin through two hollow pins.

  • So it looks like you could design a drop in trigger module that only used the existing pins as indexing/retaining points and have different axle pins for the trigger/hammer and not violate the patent. Or I guess you cold use non hollow pins for your trigger/hammer and use a stud to index the unit in the normal pin location.

  • jaimeintexas

    I lean against a system of patents. I see its merits but as time goes on it becomes infinitely complicated and impossible to manage.


    stephen kinsella patent intellectual property

    if you are inclined to read more on the issue.

    He has been dealing with the issue for a long time. I have read his writtings… many years ago.

    • Vitor Roma

      Can’t recommend Kinsella enough!

  • Glenn Bellamy

    So who is this unidentified patent attorney guest author?

  • Mystick

    Uh…. how is this not a “bushing” that simply has more longitudinal length and radial? Pretty sure someone has used a bushing and pin arrangement prior. I have seen split-pins used as mounts for a smaller solid pin(which seems to be what this is describing).

    Also, as a similar patent that used this arrangement was dismissed as prior art, how is this not also prior art? I just don’t see Mossberg having a leg to stand on here.


    The HAC 7 rifle designed, and sold by Holloway Arms Company featured a hollow pin, around which the trigger group worked, and a pin through the receiver, and hollow pin that retained the trigger group. This was put into production, and public domain in 1983. This is shown on the HAC patent for their feed mechanism. The trigger design was considered obvious, and no patent was applied for.

  • me ohmy

    never buy a mossberg….