Crane Using Lightweight .50 Cal Ammo

Special guest “18D” sent us this post on polymer cased 50cal ammo being tested at Crane. Stay tuned for more from 18D in the coming months…

Naval Surface Warfare Center- Crane, has been quietly testing polymer cased ammo for the .50 BMG. The best part about this new ammo? It works in conventional weapons systems. This means that our troops can benefit from the lightweight of polymer cases right now, instead of 10 years from now.

It is almost identical to the standard M33 ball round, however with a significant weight reduction. It features a clear polymer case, with a standard brass head fused at the bottom. The polymer cased ammo comes from an aerospace company called Mac LLC., who started a special division specifically to deal with “lightweight polymer solutions for the lightening of components”.

The new ammunition is being tested primarily in heavy machine guns, and has been performing very well.

The most exciting thing about this new technology is that it has already been type classified as the MK 323 MOD 0. This tells me that the new ammo has already proven itself and is here to stay. However it is unclear when or if the MK323 will be fielded in large quantities to the warfighter overseas or used for training.

Either way, the MK 323 MOD 0 will give the troops on the ground a significant weight reduction as opposed to standard brass casings. This will allow the warfighter to carry up to 40% more ammunition.

— 18D

  • Sammy

    Should I do a full-length resize, or just neck-only with these when reloading?


  • kirk

    I worked with a company in upstate NY who was trying to develop something similar. Can’t remember there name, NATEC I think. Know they were having issues bonding brass casing to the polymer shell. durring extraction the brass would rip off and the spent casing would jam up the weapon.

    • FormerSFMedic

      Another problem they had was with consistency. Some of the ammo was good to go, while some was just poorly loaded. Accounts of testers pressing the round on a hard surface and being able to dislodge the bullet completely from the case were common. They had reliability issues as well. I believe they went out of business not long ago.

  • mpower6428

    man oh man i sure hope they test this stuff FOR REAL, and not just take the companies word for it after a few hours of range testing.

    • FormerSFMedic

      The military isn’t going to type classify anything unless they have tested it and they plan on using it. Sure some stuff gets prototype lassified. But MK 323 MOD 0 is not a prototype classification (i.e. MK 262 MOD 1, MK 211 MOD 0, etc.). It also says they’ve been using it In machine guns. Nothing is going to put polymer cases through the ringer like a belt fed machine gun.

      • mpower6428

        i wish i was as sure. again, taking a companies assurance that “everything will be fine” hasnt done you/our servicement much good lately.

        it would be nice if we had a bunch of crusty veterans on a gov. payroll and no risk to their bonus take this stuff out and test is until it breaks. not just in extreme enviorments and conditions but also maybe a little scratched or frozen or scorched or shocked and tell us “OBJECTIVELY” what it is capable of doing and what its not capable of doing.

        those days are over i guess.

        • Skinny

          Did you actually read SFMedic’s post?? He just addressed everything you repeated from your first post.

  • Question

    Hasn’t polymer cased ammo tested previously and shown to commonly have problems with case ruptures? Is there anyone in the know that could explain what the difference is now?

    • FormerSFMedic

      Your right, previous attempts at polymer cased ammo have not been very successful. Those that got it to work, couldn’t sell it because of consistency and reliability issues. Case ruptures were a big problem. Polymer cases for the most part require a fully supported chamber. The difference now is the quality of polymer. Companies were using polymer similar in composition to say a Glock. Now they are using some really high tech stuff. Notice in the article it says the manufacturer is an aerospace company. Not Black Hills or Hornady for example. This polymer is the stuff they us in spacecraft and airplanes. That makes a high difference.

      I’m betting a company like this does some pretty substantial testing as well. The aerospace industry is a lot different than the ammo industry.

  • Lance

    They did this with 5.56mm 6 years ago and it didn’t preform well some necks would brake off in a chamber of a M-4 or M-16. The enlargement to .50 BMG is too dangerous that’s alot or heat and pressure for plastic to take on. Aluminum is stronger but it too cant hold up well for even pistol ammo.

    • nraddin

      There has been polymers around for decades that are far stronger that aluminum. The problem with polymers is that tend to either to ridged (so they crack or snap under stress) or to ductile (So they bend to easily). Strength of the material is less an issue in this that duplication of brass. You need it to be strong enough to take the blast and ejection, heat resistant enough to not melt in the weapon, yet flexible enough to stretch (All the projectile to escape).

    • Duke the wise

      Someone most likely already bought of that. Did you not notice the neck of it had been changed? I am an engineer, and the fact that it is less steep means that it has more strength when pulled out of the chamber. Also, aluminum melts at relatively low temperates. The new plastics they make are amazing, they can custom make a batch with the properties they want in it ie. high melting point. Plastic is definitely the way to go.

      • Duke the wise

        Stupid iPad…

      • FormerSFMedic

        Wow, nice observation. The neck has indeed been slightly modified. Of course experienced reloaders know that a slight change is a big change in the performance characteristics of a cartridge.

    • Dumb Grunt

      Lance- Aluminum cased pistol ammunition has been available and used successfully for years. Case in point, CCI/Blaser ammunition; it is reliable, accurate and affordable for those who don’t reload. CCI/Blaser ammunition is not reloadable. As for rifle ammunition that is a different animal due to pressure differences, rifles operate at levels much greater that pistols with a few exceptions.

  • reflexivefire

    Also helps out in a time when mineral assets (brass in this case) are through the roof!

    • FormerSFMedic

      Good call Jack!

    • eric

      And a polymer composite engineered to the exacting specifications required for a cartridge in a military chamber I do not think will be cheaper due to the intensive manufacturing processes, especially after the cost of the R&D is factored in. My question lies in how the uniform the construction is in density, tensile strength, and elasticity; and if its some form of composite matrix, how uniform the inter-layer bonding is. The problem I see is that while it is quite a small part of the pie, completely irrelevant to MGs and 90% of infantry, a polymer case cannot replace brass for match grade ammunition, as the wonderful thing about metal is how uniform the metal can be throughout the entire case, and case to case. The temperature control in the production of brass casing and the other fantastic metallurgical processes we have enables us to produce brass that will expand almost perfectly uniform at a repeatable rate and do so almost the same between cases because of the very simple ductility characteristic of metals. And as a materials engineer I’m really looking forward to the jobs opening up down the road.

      • FormerSFMedic

        Your absolutely right Eric. Polymer cased ammo does not work very well for match type loadings. Although you have to keep in mind, a sniper or precision marksman will not carry nearly as much ammo for their precision rifles as a trooper would for a machine gun. So the sniper won’t save as much weight. That’s what makes this ammo perfect for the M2HB.

        • reflexivefire

          I would love to hear from both of you as to what you’re thoughts are about caseless ammunition…

  • Duke the wise

    They should do a plastic case for the 5.56’s. Heck with telescoped cases, this is the way to go. If it works on a 12 gauge then it works for rifle cartridges. Should have put this in the m885a1 too.
    If we would do this to the .308 then it would solve the weight issue and we could get them back.

    • FormerSFMedic

      Thats interesting you brought up telescoped cases. I have seen the telescoped ammo perform in person, and can tell you it works very well. The problem is the ammo requires substantial modification to the weapon its used In or a completely new weapon all together. With new weapons trials going on as we speak (write), and the operations in Afghanistan continuing to heat up, making big changes to weapons and ammo just isn’t practical. With the MK 323, troops overseas can have the benefits of polymer cases today. Imagine this tech in 5.56 or 7.62. That makes a compelling argument for the 7.62 comeback.

  • JimS

    Seems hard to believe that 40% of the weight of a loaded 50 BMG round is the forward 75% of the length of the brass case.

    The powder charge weight is the same.
    The Bullet is the same.
    The rear 25% of the case (which is the most dense) is the same
    Someone chop up a piece of 50 brass and weigh it.

    Even if it were only 25-30%, it would still be nice though, IF the reliability is a wash.

  • JimS

    OK, I just did some math based on actual weights of powder, bullet and brass and a guess at the % of weight savings they might get out of that amount of brass eliminated. I came up with an overall/total weight reduction of 32%, so 40% seems within the realm of reasonableness…

  • KLP

    Almost a third of the weight reduction of .50 BMG sounds pretty good and 40% sounds even better. Doing this with .50BMG is probably because working with as large a round gives you room to make thicker case walls, whereas a polymer case 5.56×45 probably doesn’t give the polymer enough leeway to be reliable. I really hope this tech can scale down at least to a .308. The question then is going to be, load up on a ton of 5.56, or get the weight savings and leave it, or break even with .308.

    I also do like that the case is blue and glittery.

  • chockblock

    They better update the TM’s. We had a problem with headspace, the cases on our .50 brass were rupturing. I’m guessing this is the chocolate to the M2E2/M2A1 peanut butter….

  • coolhand77

    This is a step in the right direction. Start with the larger scale, test it, tweak it, make it work, then start scaling it down for man portable smallarms. Its kind of funny, the M2 and .50 BMG are actually a scaled up M1919 and .30-06 respectively [yes I know its not a 100% comparison, but you get the point]. Now they are starting with the big boy, and looking to scale back down.

  • Alex (not a gun nut)

    Talked to someone about 2 years ago who was friends with a tester of this amo, turns out that when firing it through an unmodified 50cal machine gun that it would shoot faster, not sure how much faster but it was very obvious. Don’t remember the name of the company though, and I don’t know if it’s the same as the one as made the amo mentioned above.

  • Alex

    I think that the CG might be interested in this amo for the helos.

  • Lance

    Yeah but most local Sheriffs Dpts left it it cracks too easily. as for plastic rifle ammo they tried this before with 5.56mm and the necks broke off during firing too easily. Not good

    • Dumb Grunt

      Lance- Again, pistol ammunition operate at very different pressure levels than rifle ammunition. That is why CCI/Speer did not manufacture rifle ammo for the Blaser line with aluminum cases. The CCI/Blaser aluminum cases are designed for one shot usage, not to be reloaded. If the case “cracks”; the question is when,how and why did it? The most important is did it cause a malfunction? If it did not, and the “crack” occurred after ejection, then there is no problem at all.

  • eric

    Pretty similar concerns for conventional ammo, whether or not the solid propellant will attain a consistent density to ensure a continuous burn rate, as I would really hate for there to be some kind of air bubble that causes the round to misfire and then have to clear an FTE with a partially live round, or have a round lodge in the bore. That’s a really nice thing that you don’t have to worry about with conventional propellant, as the powder just falls into form. From the looks of the polymer cartridge and the band wrapping around neck I’m guessing they have some of the sealing issues worked out, but that’s another concern in caseless ammo. The physics of conventional ammo is pretty neat, as while the bullet is seated in the cartridge, the force from the expanding gas is placed on the back of the bulled and the floor of the case, with some going towards the expansion of the case which can actually help maintain a slightly more complete seal on the bullet as it exits the case, lessening the amount of gas that escapes around the bullet. Also, the energy transfer from the weapon to the propellant is much higher as the case would usually dissipate some of this and slow the transfer, that and that there’s no case to insulate the chamber walls and there’s more wear on the chamber walls due to the direct exposure to the combustion. Just a few thoughts.

    • reflexivefire

      Can you break down the physics in regards to the old Soviet “silenced ammunition” in which the cartridge contains a kind of piston that pushes the bullet out and the gas remains inside the casing? Small Arms Review covered in a year or two ago and I was just wondering what your thoughts are about it.

  • eric

    Also, do you guys have a suggestion box or an email? I have something interesting I’d like to get you guys’ opinions on. I’ll give you a teaser: Semi-auto .338LM’s.

  • Charlie Taylor

    Do you mean faster as in rate of fire or faster as in the FPS of the projectile?

    • bbb

      I wonder about that too. A lighter casing could mean it could be ejected and loaded faster…which would increase the cyclic rate in theory.

      The only way FPS could be increased would be through increased pressure, which doesn’t seem likely with a polymer casing.

      • Alex (not a gun nut)

        Sorry about that, I meant faster “rate of fire”.

  • FormerSFMedic

    The SP-4 ammo is a cool design. It was a concept that actually worked and from what I understand is still being used. There is essentially a piston between the powder and the bullet. When the charge is ignited, the piston propells the bullet. The cool part is that the piston continues forward after the bullet is released and seals the neck from allowing gases to escape. Since its the gas that makes firearms so loud, the sound is contained within the case.

    I think there could be a niche use for this kind of ammo. However it probably isn’t realistic for high pressure rifle cartridges. The complexity of loaded ammunition is of concern as well. Anytime we add more parts to a simple design, we add weight and run the risk of reliability issues. You are more than likely going to run into cycling problems with the gun as well. I’m not sure how accuracy would be with this system either. Accuracy is dependent on many factors, but its the gas pressure exerted on the base of the bullet that makes a difference right before the bullet leaves the gun. This system eliminates that, so its hard to tell if that would negatively effect accuracy or help it.

    Either way, I like the idea for short range use in handgun weapons systems.

  • FormerSFMedic

    Something I left out was the law of conservation of energy. Since energy can neither be created nor destroyed, I would think there would be some heat concerns as well. Not only that, but how will the bullets be seated In the cartridge. There has to be some concern that if the bullet Is too tight, the round might not be propelled. If the round Is too loose, cycling could cause bullet setback and drive pressure up. High pressure in this design, like stated before could have serious consequences.

    • eric

      Did it see any kind of accuracy at range, or was that along the lines of the 9×39 subsonic cartridge? You also have to remember that that system also traps most of the sound energy in the chamber (some will be transferred to the surroundings as metal is one of the best sound transfer mediums as it approaches a more perfect crystalline structure) so you might also see some of the longevity and durability issues of caseless ammo, but these are things that should be able to addressed. My main point to the issue of match ammunition is that these systems will never completely replace current ammo (lasers will, probably) and that there will be much much larger production costs associated with the level of training, manufacturing techniques and materials required for these systems. Anyone know what the chamber pressure ratings are on the new caseless LMGs that are being evaluated are? I’d like to see what the difference really is. I’m really weary of SP4, as you don’t have a continuous propellant source throughout, it’s basically a barrel-launched grenade where the bullet lodges in the muzzle. As mentioned, there’s little need for this in rifle cartridges as the bullet is supersonic and would only aid in concealing the shooters position to some extent. Overall I would say it’s kind of sketchy at best and not worth the reliability issues FormerSFMedic addressed (which he did completely as far as I would elaborate) for the stealth advantage considering you might not be able to defend your position if compromised. The one thing I would add is that you’d kill about 70% of the recoil and the muzzle flash entirely since the gas is contained within the rifle, but in order to have any automatic weapon would have to be a very very short stroke piston system fed by the chamber, which would deteriorate the muzzle velocity consistency. Could work well for bolt guns.

  • bbb

    Blazer is crap. The rim shape is all wrong, so some guns will fail to eject the casing almost every time. They made it this way so it wouldn’t fit in a shell holder, because they cared more about making sure you didn’t try to reload the casing than whether or not it will function with every weapon.

    • Dumb Grunt

      bbb- Blaser ammunition is designed to fit and function in the SAAMI specification chambers. One reason why that ammo may not function in some specific chambers is because of dimensional differences or maintenance problems(i.e. dirt/fouled components), maybe operator error. The rim shape is part of the SAAMI specification. The way CCI used to make Blaser ammunition is by using Berdan priming instead of Boxer priming. CCI/Blaser ammunition is as reliable and accurate as any ammunition made by CCI/Speer.

      I have worked at several ranges and have shot competitively for many years, I have yet to observe a malfunction with CCI/Blaser ammo that would be exclusive to the ammunition. It is a good product.

      • bbb

        My gun is clean, but it’s an old design (S&W Model 39-2). The rims are visibly thicker than those on reloable brass. Even the Blazer Brass stuff is like this.

        For the same reason, it’s VERY hard to put Blazer revolver ammunition into Safariland speedloaders or any type of speed strip… you have to force it in.

        If you have a newer gun, it might work fine. But I think any standard ball or FMJ ammo that doesn’t work with every single gun of that caliber should be considered a failure.

  • Dumb Grunt

    bbb- I’m sorry that CCI/Blaser ammunition doesn’t work for you. I have had no problems with it at all. My pistols and revolvers are of old and relatively new manufacture; I have experienced no malfunction due to the rim thickness. I use safariland speedloaders exclusively and had no problems. Others, I have observed who use other brands of speedloaders have had no problems with the aluminum case either.

    As in all mass manufacturing you build to fit in general as many variations as you can, but in no way can you mass manufacture a cartridge to fit all chambered for a caliber, just sometimes it just doesn’t work for one reason or another. You see SAAMI specifications have tolerances (variations in dimensions) and for you CCI/Blaser does not work. For example, let’s say you have a custom match rifle chambered for .308 Winchester and several boxes of match ammo from various manufacturers, you discover two brands of ammunition that will not chamber and three brands don’t group well. Is this the fault of that ammunition maker or is it the fault of the custom smith who cut your chamber or is it just the tolerances just came out that way? In truth it could be a combination of all three and you won’t know until you do a detailed analysis.

    That is just the way it is; each gun is an individual and no two are completely identical.

  • Tony Williams

    Just a comment on the weight reduction: “up to 40% more ammo” is not the same as a 40% weight reduction.

    The math works like this: one .50 cal round weighs c.115 grams. 100 therefore equals 11,500 grams. If you are carrying 40% more ammo for the same weight, that means that 140 rounds also equal 11,500 grams – so one round equals 82 grams. 82 g compared with 115 g is a reduction of 29%.

    In fact in an MG the reduction would be less than this because the weight of the belt links needs to be added in. Unless they are making these lighter too, they will continue to weigh 17.5 grams each. So each round of belted ammo will weigh 99.5 g compared with 132.5 g at present – a weight reduction of 25%. Still very much worth having, provided there are no disadvantages.

  • P. D. Quick

    Wow …a troop can carry 40% more 50 BMG?????? A can of belted BMG is a can of belted BMG. Will I now carry 1.4 cans of belted BMG???????

  • 25s7e

    Extraction of ammunition also depends on friction of the case against the cylinder wall, so in theory it could slow the MG

  • 25s7e

    I see this being more useful in the m107a1 than “Ma Duce” the main advantage of brass casings is the fact that they extract head from the weapon when ejected.

  • Kathy S.

    J. – very cool, I have always wondered about that Soviet piston pistol!

  • John Friedson

    Look at the color of the bullet – I’m betting it is copper, not lead, and part of the weight ‘savings.’

  • SCN50

    I have tested this ammo, and the “match” variant with a opaque green case in a Mk15 (my civilian version) bolt action rifle. My partner and I have been helping to test this ammo for the past 3 years. FYI, the bullet is a standard M2 ball bullet, no difference there. The black band you see is the “tar” waterproofing sealant. We have tested both variants in my bolt gun and his M82 Barrett with mixed results. I had problems after several rounds where the very lip of the case separated and stayed in the chamber, and after a few rounds, I could no longer chamber a round. My partner has been able to shoot in out of his M82 without problems. We have been providing feedback and suggestions to the manufacturer for 3 years now, and I do not believe they have all the bugs worked out yet.

  • Brian B. Mulholland

    Extraction of a metal case from the chamber serves as an exhaust, removing a good deal of unwanted heat. The caseless 255 mm round originally intended for the F-15 was ultimately dropped, in part because the lack of this heat exhaust proved destabilizing. I wonder how well the polymer cases do, in that regard.

  • Brian B. Mulholland

    Brass cases serve as a radiator, and their ejection removes a good deal of waste heat from the chamber. I wonder how well the polymer cases function, in that regard.

  • Sam Lord

    Actually brass cases act as heatsinks compared to most polymers. The brass absorbs a small portion of the heat of combustion. A portion of that heat is transferred to the chamber before extraction, and the rest of course travels with the hot case. The polymer case will typically absorb less combustion heat so the propellant required for a given MV is a little less. But the chamber is heated *less* by the polymer case than by the brass case. That is good, but the polymer case similarly absorbs *less* heat from an already-hot chamber. The result is that polymer cases are more efficient in propulsive operation, but allow more rapid heating of the chamber. That increases cookoff and premature heat damage to the chambered polymer rounds, and rim separation in many rapid-fire events as mentioned earlier.

    • Sam Lord

      Sorry, please replace “rim separation” in the last sentence with “head separation.” The important difference between the two case types, apart from mass, is thermal conductivity.