Ultra Compact AR-15 “Ribbon Spring” Concept Magazine

For years I have dreamed of a rifle magazine that could turn 180-degrees. What I could never figure out was how to design a spring and follower that could turn 180 degrees reliably.

An Australian reader emailed CAD drawings of a nifty 30 round compact AR-15 magazine he has designed. The magic lies in the design of a spring, which has he did not include in the drawings he sent me because it is not yet patented, but he assures me it will function.

The downside of this design is the need for an ambidextrous magazine release. I think this design in a 40 or 50 round capacity model would be handy.

If you are a manufacturer and are interested in producing the design, you can get hold of the designer Richard Urwin at r_urwin@hotmail.com.

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.


  • This would be nice for a bi-pod mounted weapon in the pron position where you’re usually limited to 10 or 20 round mags.

    • Richard Urwin

      Hi Pa Stubbs,
      This is the intended market for this product. I am grateful you have pointed it out.

  • Higgs

    Would be a bitch to put in pouches.

    • Geodkyt

      Not if you make it the same size as a pair of 20-rounders clipped together. Just buy pouches set up for even numbers of magazines. “Shim” the bottom of pouches that are too deep for them (30-rounder or SAW pouches) with cleaning kits, pocket survival kit, spare batteries, waterproofed dry socks, friggin’ stripped down personal hygiene kit — ANYTHING you need to have on your webbing, but won’t likely need in the middle of a firefight.

      • Higgs

        Then you can only carry 30 rounds for the space of 60. At least in regards to a 30 round mag, This is a solution lacking a problem. If shooting prone is really a issue for you, then id rather carry a punch of 20 rounders.

  • Seems like quick mag changes would take some getting used to since there are two “ends” side-by-side?

    • Geodkyt

      Think Magpul loop floorplate — the floorplate side is lower than the feedlip side, so you could have a nice, ergonomic, easy discriminated by crude feel handle, that doubles as something you can hang on a carabiner(less chance of screwing it up than CURRENTLY exists with milspec M16 mags, actually!) WITH a loop in place, it could be just shorter than the feed side, and the loop would allow access to the bolt latch if it curved to port, rather than to starboard (as the drawing shows)

      I do think that curving to port is a much better idea, provided you do not block access to the bolt latch. While I like the ambi mag catch I have, it IS slower than being able to use the normal button most of the time. Stabbing a bolt latch through a loop is less of a hindrance, IMNSHO. (Of course, if you have a BAD latch or other “ambi” bolt latch, problem solved, even if teh portside half of the magazine totally blocks the standard latch.)

      Better than a fixed floorplate loop, put a fixed loop that has a spring loaded gate like a carabiner on the floorplate, so you can (without looking or needing a high degree of fine motor skills) snap empties to ANYTHING that fits into the loop, including suspender straps (for those still using “brace & belt” ALICE type systems) or a lanyard for a non-combat piece of kit (like your compass).

      A box that basically matches the size of a pair of 20-rounders clipped together (call it a 35-40 round capacity) would give you significantly increased onboard ammo, the ability to clear ground from prone or low bipod (because it would still be shorter than the pistol grip), decent balance (because you aren’t hanging a 50-100 rounds off to one side like the snail drums), and SHOULDN’T overload the mag catch (because you’re not hanging 100 rounds off it.)

      Pouches that hold even numbers of 20-round mags and can accomodate 20-rounders clipped together (or this idea) are available OTS, and 30-rounder or SAW pouches can be easily modified — stuff a cleaning kit or other “critical, but not needed DURING the firefight” kit in the bottom of the pouch to raise the floor enough. . . two solutions for the price of one.

  • Andrew

    Isn’t kinda weird when you see someone else is working on the same thing you are, yet the two of you never knew the other existed?

    A constant force ribbon spring could make that turn nicely but my experience has been that constant force springs can be tricky with the variable mass of an unloading magazine. I wish him all the best, though.

    For a look at how it might work, see Ruger 10/22 large capacity magazines.

    • Richard Urwin

      Hi Andrew,
      You know I am glad you comment we should look at collaborating?

  • Reverend Clint

    couldnt they just have the magazine bend the other direction to solve the release issue?

    • yeah but Aussies wont like driving on the “wrong side”…LOL

  • Kenny Blankenship

    Coil springs not yet patented? US3087270, US4027415, US4776122, US4879828, US4888899, US5113604 all beg to differ. There are probably more. Not to say that this isn’t a patentable innovation… it definitely is, and looks promising.

    • Richard Urwin

      Hi Kenny,
      Thank you for your comments. The “Coil springs”; or commonly termed “Constant force springs” or even “clock work springs” are like “Compression Springs” and are subject to jamming and tilt with the application of uneven application of force across the follower. The spring configuration I have selected to develop has a number of novel features beyond its original intention of offering anti-tilt feature which is was focused on; its those I wish to patent. I have gone through the patent process a number of time the expense and payoff is really not there for the individual inventor.

      • Kenny Blankenship

        Crikey I misunderstood then. Keen to see the final design once you’ve got the IP protected.

  • Kenny Blankenship

    The main problem is overcoming the friction encountered while pushing the round stack around that 180 degree turn, as well as in general. Why not manufacture a straight walled mag with a coil spring first?

    • Geodkyt

      Polymer low-friction magazine body inside, same for follower.

      There ARE some engineering challenges involved, but it is not wholly unfeasible.

  • Partizan1942

    The one on the picture could hardly have more than the regular 30 round capacity at least judging from the size.

    You lose a lot or reliability (probably) and because of the pistol grip you do not even get to make use of all the space you gain below the rifle when prone. Plus one would need new pockets on uniforms…
    It’s an interesting design though.
    Dunno could be useful with some sniper rifles that only have a 5 round mag. Than again it has to be tested so as not to prove yet another C-mag like fail…

  • Anon

    Maybe this would work fine with lower capacity magazines, or straight-walled conversion calibers, but I’m having a hard time seeing this work for a tapered cartridge like the 5.56x45mm when the body itself has no forward curvature.

    • Sian

      each vertical stack is under 20 rounds, and 20rd AR magazine is straight-walled. It shouldn’t be a problem.

      • C3PO

        That doesn’t suss out. . . lay 10 and then 15 5.56 cartridges on a table and see how much they curve. regardless, the mag must curve or the follower tilt. A 30 round mag has to either curve, or let the follower tilt. the force should be toward the bolt and if it tilts too much without curving, the force on the stack will tend to jam the bullets. even a nominally straight walled case like the 9mm or 30 carbine have curved magazines when going over 20 rounds – or have reliability issues and must be kept tuned and very clean (because race gun).

  • D

    Definitely fills an interesting niche. I’d be curious to see how it performed once it’s in wide distribution.

  • MemorableC

    This would be perfect if it came down just a little bit more and didn’t turn right as it left the mag well, get about a 40-45 round capacity and still not stick down as low as a 30 round stanag.

  • Trev

    How does that solve anything? It looks much bulkier than a GI mag for the same capacity.

  • Richard Urwin

    Thank you for all your comments and greatly appreciate the guys from the TFB for posting this; I greatly value all the feed back.

    In a attempt to answer some of your questions and to give a further background for interested parties.

    The origin of the idea stems from attempting to develop the most reliable magazine spring configuration (specifically a tilt free spring). Rather than addressing the design of the Follower; like most people and company’s before.

    My mindset was to attempt to overcome the short fall in using the age old compression spring in a firearms magazine. I preformed a extensive patents search for a reliable spring configuration; further I built models which in-turn helped evolve the design of which showed promise for application to firearms magazines.

    Once the design for the spring was consolidated; I started by designing a standard normal 30 round AR-15 magazine with the inclusion of the novel anti-tilt ribbon spring configuration.

    However after looking at the now truly large collection of 30 round magazines on the market (Most of them now with an Anti-tilt follower); I thought a redesign of the proposed launch product idea would be best to capture a novel subset of the sports shooters market.

    During the development of the 30 round magazine; I had extended the design to a 55 rounder with the U shaped bend. In building a quite large ribbon spring for the 55 rounder I thought it was taking too much of a large risk in development. I kept the U bend and shrunk the capacity back down to a 30 Rounder creating the Ultra Compact 30 as seen in the article above. The spring design itself will happily traverse around the 180 degrees seen in this design.

    Currently I use spring steel shinning metal for prototyping the spring design. If all goes to plan my current intention is to have the parts of the magazine 3D printed and tested with family in Florida. However I am really open to collaboration. I want to boot strap the idea into production and beyond.

    There is a number of additional firearms ideas that stem from using novel spring designs. As mention to the Steve the Editor of TFB; I would say I have taken a lot of inspiration from FAB postings. I would hope in a small way that this story help others with their projects as well.

    Thank you for reading and with regards

    • Sian

      You could always throw it up on Kickstarter and see what kind of funding materializes. You might be surprised!

      Right now I’m wondering how this idea could be applied to Saiga12 magazines. XD

      • Alex-mac

        That’s a great idea, Steve at FAB can help with the promotion of the kickstarter. Just make sure you have a nice video and everything planned that you want to accomplish with the money. Research the successful kickstarters.

        With the extra money you can hire a patent lawyer.

        I’d also look into collaborating with the Australian military. ADI or Thales. They are currently developing the EF88 and would be no doubt receptive to an enhanced magazine to go with their enhanced rifle.

      • charles222

        I’d try Kickstarter as well.

      • Alex-mac

        Here’s a free crowdfunding guide.

  • bima86

    my friend (an industrial design student) tried to figure out something like this for one of his college assignment. but he wasn’t able to fix the jamming on the 180ยบ turn, and failed. he got held back a year and had to take the class the next year.. hahaha

    I’m hope you finish this soon, I’m looking forward to see the working prototype / product.

  • SC Econ

    I understand the possible value added by this product when used with a bi pod, but how do I carry these things around? They are more than twice as wide as conventional mags and will not fit easily into any rig. The cost of use far outweighs the value added. Just dont see it taking off at all.

    • bima86

      if I’m not mistaken there are already lots of magazine pouches that could fit two magazines back-to-back, so maybe these will fit into those too.

      have you seen the surefire extended magazine (60/100 rounds) those definitely won’t fit in any magazine pouches, but they are already people who have bought them.

      • SC Econ

        These are WIDER than two mags stacked together. Most double mag pouches are already snug. Are you planning on placing one ontop of another. How fun is it to get your hand down into the pouch to fish out that bottom mag that is already too wide to be in the pouch in the first place.

        The Surefire mag comparison is moot. The comsumer who purchases one of those is willing to accept the value added (greater round capacity in a single mag) over the cost of use (it will not easily fit in a pouch). Remember pouches are for carrying more ammunition. Apples to apples. Indeed, one could argue that the surefire mags partially negate the value added of the pouch. This U mag does not add any capacity value (like a larger mag or additional pouches). It only inhibits the value added by the efficient use of the pouch.

        This mag would roll around in a saw pouch.

        This is a solution looking for a problem.

    • charles222

      SAW pouch, or a triple-magazine pouch.

    • Alex-mac

      To take advantage of the 30 round mags they’ll need special mag pouches, but there is potential to hold more rounds in less chest molle space.

      There won’t be any space savings for the 55 rounders, but obviously they’d be alot more convenient, as now one pouch will hold one magazines instead of two.

      This can be extended even more with 100 round magazines. (if possible) Alot more easy to store than drum magazines.

  • jrt

    Would you even “need” a pouch?

    Why not “clip” them onto your gear llike the old Garand clips you see stuck on straps?
    Or you could put a plastic “hump” with a keyhole divit inside the U channel to apply friction force so it will not fall off the Strap / loop / pocket.

    • W

      holy crap. retro! im actually jealous of that idea

  • Alex-mac

    Other advantages.

    The mags can be setup on ones molle vest to project outwards, enabling you to carry more mags in less space.

    Increased compactness for personal defensive weapons.

    Greater magazine capacity for equivalent magazine length all round.

  • Kevin

    A good concept, and if the reliability is there, it might have legs. My advice is to make some prototypes and get them dirty and do some shooting. I think, like others have said, it might be a better idea for 7.62 rifles or mag fed shotguns. There are just so many solutions for the AR 15 mags and through them all, shooters have pretty much voted on conventional 30 rounders, with poly mags just recently becoming popular. Saiga box mags are ridiculous.
    I like the idea, best of luck.

    • A u-shaped 12-round Saiga-12 magazine is a good idea. The straight ones are like 2 and half feet long – ridiculous.

  • Mike Knox

    You know, you really can’t tell hoy good it works until a prototype’s tested. Anyway, nifty idea though. Maybe another column on the other side merging at the bend might be a good idea, after all, it uses a ribbon spring..

    • Richard Urwin

      Hi Mike Know,

      (as abstract as the following description might read)It does not use a ribbon spring or constant force spring that has been used in previous designs of magazine before.

      A separate wedge in the casing is not required for spacing of the traversing band. However a small allocation cut out from the space follower is required.

      With regard

      • Mike Knox

        So merging springs are out of the question?

  • Ian

    My favorite part is how it doesn’t account for the cartridge’s taper. Or that the ammunition won’t align itself well at all going through that sharp of a turn. Then again I’m “old fashioned” and think that compression springs are just fine.

    • Richard Urwin

      Hi Ian,

      Thank you for your comments

      You are right on all accounts! compared to a compression spring there are a number of inherent benefits to my way which without seeing are not obvious.

      Given the comments on this blog it has inspired me to continue and I hope to have a video showing a taper round traversing a 180 degree bend for digestion in the near future.

      Fingers crossed!

      With Regards

  • Lance

    No real sense for one for a 30rd mag but it be cool for a 40+ rd mag to make the weapon not as bulky with really high cap mags.

  • D_A

    I think this is actually a pretty neat design, and I hope that the designer is able to follow-through to production.

    I can’t help but wonder though why nobody has gone the same route as US PALM in designing a quad-stack, curved, short 30rd mag but for the AR?

    In case you’re not sure what I’m talking about, see here: http://www.thefirearmblog.com/blog/2012/01/19/us-palm-quad-stack-45-and-30-round-ak-mag/

    • Richard Urwin

      Hi D_A,

      Thank you for your comments.

      Personally my view is that the larger the number of moving parts; as well as the larger distance traveled the greater probability of issues.

      The spring Design I have adopted uses 3 moving components + the total number of bullets left in the magazine.

      The Russian designed 60 round magazine is amazing in terms of simplicity of design; Link: http://www.thefirearmblog.com/blog/2010/06/25/russian-60-round-quad-stack-5-45x39mm-magazine/

      And I believes condenses the design to the most reliable with the lest parts.

      With regards

  • Rootshot

    A long time ago, I used to have a Ram-Line 14 round Ruger MKII magazine that used a ribbon spring. The spring partially coiled up inside the follower. It’s a very novel design.

    It worked modestly well, but the amount for force it was able to exert on the column of ammunition was considerably lower than a traditional magazine. I would not trust my life to it. I would also have concerns as to the longevity of such a spring. Eventually, some cleaning solvent attacked the plastic and it was kaputt.

  • Fred

    Couldn’t the mag be curved to the other side to keep better access to the mag release button?

    • El Duderino

      Seems like a “duh” to me.

    • Richard Urwin

      Hi Fred,

      Yes the mag can be curved to the other side. I am in the process of converting this now given the comments posted.


  • Komrad

    Could the stacks be made longer so that overall length was similar to a 30 round design? Might be a good way to get a higher capacity without additional length, or it might just jam more. Just an idea, feel free to use it.

  • Mike

    Going to have trouble if you don’t account for the taper of the cartridges.

    With a bipod mounted AR, your rate of fire is generally going to be lower, making a 20 round magazine more reasonable. If you need a higher volume of fire, just run a regular 30 or bigger and ditch the bipod. Rest on the magazine, works great.

    • charles222

      Or just extend the bipod legs so a 30-round fits; done this myself plenty of times.

  • 6677

    Only issue I see (that hasn’t been mentioned repeatedly anyway) is with bullpup weapons, much deeper magwells, this would probably just jam up, however a similar design might still work, larger radius on the U bend and a longer length on the section to be inserted into the weapon.

  • Marc

    Rehash of the MGW 90 round drum idea this is far from new, the Steyr Box mag and the Johnson rifle along with the MGW drum will kill his chances of a patent way too much prior art of this type out there.

  • Harry

    Hey, if you want to maintain an ambidextrous mag release, you could shorten the part of the mag after the curve so it ends below the mag release and doesn’t obstruct it on either side. You could then extend the part of the mag before the curve so you still have 30 rounds total.

  • Paul J

    If it’s not a wire spring, it’s pressurized air.