Review: Semper Paratus Arms AR-15 Armorers Course

    Meet William Larson of Semper Paratus Arms. Think of him as a doughnut-fueled AR-15 Yoda with near three decades of experience building and diagnosing the AR-15 platform. He has much knowledge, and you want to possess it.

    But you might be thinking, Patrick, I am just a recreational shooter. I don’t need an expensive class about how the AR-15 works, I have the internet. Well, friend, there are some things that the internet just can’t teach properly. For example, when searching for “how to build a lower” there are a ton of videos out there that show several potentially damaging ways to install roll pins as well as other wrong information like “thread locker is good enough” for gas key screws and castle nuts.

    Experience tells me that thread locker is not enough and some of those YouTube instructional videos are not only wrong but can turn your exciting day of building a lower into one of dread that involves half an hour Googling how to repair a broken trigger guard ear and a trip to the auto parts store for some Quick Steel putty, some screws, and some threaded inserts. Sadly I found out the hard way on my very first SBR. Hopefully, you don’t make the same mistake.

    William Larson of Semper Paratus Arms

    Semper Paratus Arms keeps the class size to a manageable level of about a dozen students even though he could double or triple the class size and still sell out. This allows him to spend some quality time with each student if they happen to be struggling with any part of the course, be it questions about the presentation portion where Will covers the specs of a properly built AR-15, operation, malfunctions, and history or if the student is struggling with part of the assembly process.

    Semper Paratus Arms AR-15 armorer course

    As I said, there is almost an entire day dedicated to Will’s expertly put together power point. You might groan about this, but frankly, I found the power point day to be the most useful part of the class. I took away quite a lot of information about the platform that I previously was unaware of. A better indication of how engaging the presentation was would be the amount of notes I took. Normally I am not big on written notes and prefer to just pay attention to what is said and roll with that but the amount and quality of information required me to break out the laptop and take notes on everything.

    Semper Paratus Arms power point

    Other students were writing down what Will had to say in a fast and furious manner, and rightfully so. I think I must have typed just about everything on the slides as well as some things Will said and added my own notes as well.

    AR-15 Armorer Notes

    When we got to the hands-on portion of the class, I got kind of excited to watch someone who had put together literally tens of thousands of AR’s for some top-tier manufacturers like Bravo Company as well as functioned as an armorer for several private security companies like Blackwater or Triple Canopy.

    Sionics Lower Build layout

    Watching Master Yoda explain each step of the process to new builders and experienced ones like myself, why he was doing it that particular way, and what is the right tool to use was pretty cool. When Will was done with the lower, it looked like it had come out of a factory without a mark on it.

    He showed us two ways of building the lower, one with a bare minimum set of tools, the other with the right tools. I was most interested in doing it the right way, but if I was in a bind, I could make something happen with nothing more than a plastic .223 bullet, Glock punch, and a couple roll pin punches.

    William Larson of Semper Paratus Arms Building an ar-15 lower Semper Paratus Arms Minimum Toolkit

    Installing the receiver extension (buffer tube) was done to the Mil-Spec, and each one was staked properly with a punch in two places. Prior experience tells me this is absolutely necessary after having the buffer tube rotate enough to lose a spring during firing on two separate factory built rifles.

    Semper Paratus Arms Torques A Receiver Extention Proper Castle Nut Staking

    Then we got to the really fun part, going through the rifles that students brought and diagnosing failure points. First up was the bolt carrier groups where Will checked the staking job with a bit driver. If he is able to loosen the screws using a standard screwdriver handle, the screws are replaced with proper replacements, and the gas key is staked with a MOACKS Plain staking tool (Click the link for a review).

    Semper Paratus Arms Moacks Plain Properly Staked Gas Key

    Next, is checking to see if your 5.56 chamber really is 5.56. To accomplish this, he breaks out the dreaded chamber reaming tool and checks to see if there is any material removed. If there is any metal cutting by the chamber reamer, it is obviously not to spec. Several rifles with extraction issues were offered up to the reamer gods, all failed the test and now have a properly sized chamber.

    Semper Paratus Arms Chamber Reamer

    You can see just how much metal is on the reamer. Yikes. At least is if fixed now thanks to Will.

    Chamber Reamer Aftermath

    We ended the class by going through the famed Semper Paratus Arms box of shame, where Will keeps all the failed parts that were not made to last. Everything from barrels that have lost their barrel extension (this one is called a CIA barrel by Will due to there not being any markings on it whatsoever.)

    Semper Paratus Arms Box Of Shame

    The crap gas blocks and front sights were fun too, everything from gas blocks that needed to be cut off to front sight posts made from cheap aluminum, each one of these was replaced with a quality part.

    Semper Paratus Arms Box of Shame

    I also wanted to share this beauty. This is a bead organizer from a hobby store that inspired me to pick up a metric ton of extra parts. I expanded the selection a bit, and my small parts tower includes gas key screws, Crane o-rings, trigger guard roll pins, gas tube roll pins, bolt catch roll pins, forward assist retaining roll pin, and ejector roll pins. Now when I am repairing or upgrading one of my rifles I no longer have to re-use roll pins incorrectly since roll pins should only be used once.

    Semper Paratus Arms Small Parts Kit


    I was a bit on the fence about taking Semper Paratus Arms’ armorer’s course when I heard he would be in town since I thought I knew everything I needed to know about the AR-15 platform. How very wrong I was. Not only did I learn a lot more about diagnosing malfunctions, but I also learned how to put them together properly. Previously I had no issue with putting a lower or upper together, but not only is it a whole lot easier now, but I no longer run the risk of blemishing the receivers.

    If William happens to be in your area offering one of the Semper Paratus Arms AR-15 builder courses or even the two-day Armorers Course I HIGHLY recommend taking it. The builder’s course is only $150, that gets you a day with Will to pick his brain, build your own SIONICS AR-15, and even get some of the information he passes on in the Armorer’s Course. Outside parts kits are not allowed in the builder course due to compatibility issues and the limited time during the class, he also provides all the tools that a builder will need. The best option would be the full on Armorer’s course, priced at $350 per student it is a pretty solid value if you want to take your understanding of the AR-15 to the next level and beyond.

    For those in law enforcement, some states do offer credit for Will’s course. If you are LEO and are unsure it is best to check with Will to see if you are covered, I know that Texas LEOs may be able to get credit. But again, make sure you check with Will before making that assumption.

    Check out Semper Paratus Arms either on their web page HERE or their Facebook page HERE. I also want to extend my thanks to the other students for putting up with my constant photographing and endless questions as well as Ryan for setting the whole thing up.