Personal Defence Weapons (PDWs) are weapons meant for soldiers who do not have shooting at the enemy with small arms as an important part of their job description. Support troops, tank crews, helicopter pilots and even infantry platoon leaders qualify.
Early examples of de facto PDWs were the revolvers or pistols used by officers and the relatively weak M1 "carbines" of the U.S. Army in WW2.
Germany used UZI submachineguns for that purpose during the Cold War and introduced the dedicated PDW "MP7" with its tiny bullet since. The pistols in use with the Bundeswehr are not really de facto PDWs; their primary utility is in being guns with ball cartridges for escorting men outside of barracks who carry war small arms with useless blank cartridges. This way nobody shoots a gun with deadly munition while thinking it's loaded with blanks and there's still protection against people with pitchforks overwhelming and robbing an entire infantry platoon on a foot march.
PDWs are not really meant to be used against hostile troops even in wartime. They would only be used to shoot in anger under extreme circumstances. Most likely, the user would stand no chance due to morale, (lacking) combat training, lacking night vision and/or circumstances anyway.
PDWs do serve purposes, though. They make the user feel armed (and thus respected as a soldier) and they may be used to control prisoners of war or to scare away civilians who interfere with military operations.
PDWs do thus not need to be very powerful or high end. NATO was famously looking for PDWs that can penetrate a certain bulletproof vest concept (titanium plate + aramid layers) at a useful distance. this ruled out submachine and probably served no other purpose.
The cheapest way to create a PDW would be to build some super-cheap submachinegun such as a modern Sterling submachinegun. It would fail to be perceived as a respectable military weapon nowadays, though - and thus fail the morale job of the PDW.
In practice you could use just about any assault rifle or battle rifle (G3, FAL) to equip non-infantry and non-dismounted scout troops, but those would be quite cumbersome practically all the time they are carried. Thus they would not be carried for almost all the time.
I pondered about the concept of a PDW long before I started this blog in 2007, and just in case I ever need a blog post and can't come up with any decent topic I'll write down my currently favoured concept for a PDW (unless the armed forces have enough old assault rifles / carbines in their stocks):
It shall be
- lightweight
- cheap
- not cumbersome
- respectable
- with good ergonomics
- fully sable in all seasons
- built for their users (who don't get much small arms training)
- 5.56x45, 5.45x39 or 5.8x42 mm calibre (depending on standard calibre in use with the armed force)
- reason: lightweight cartridge, small recoil, penetrated soft body armour, flat trajectory makes aiming relatively easy out to 200 m at least
- chrome-lined barrel of about 28 cm (about 11") length
- reason: That's long enough for the purpose with 5.56x45 mm at least, especially with a high pressure cartridge such as EPR
- chrome lining more to preserve the weapon during 50+ years of use than to enable more shots fired
- barrel should be of lightweight construction ("pencil" barrel, outer diameter ~ 16 mm (0.625") and does not need to be armourer-level exchangeable
- few practice shots per year on average, as most PDWs would be stored for mobilization, not be in use by active duty troops
- assumed munition loadout: 20 rounds in loaded magazine (wartime only), twice 30 rounds in pouches, maybe another 20 rounds in stripper clips in a pouch
- infantrymen would carry much more munitions, support personnel would certainly not carry more on the body most of the time! Cartridges in stripper clips are a very lightweight reserve just in case the more readily usable cartridges in magazines were spent very quickly.
- 20 rds magazine loaded becuase this protrudes less than 30 rds magazine; less bulky
- an effective (but preferably short) flash hider
- the shortness of the barrel makes the muzzle flash worse, so a basic flash hider such as A2 is unsatisfactory
- handguard around the barrel with M-LOK interface on top and bottom
- just in case upgrades (or iron sights) are later deemed advisable, more lightweight than NATO rails
- forward hand grip in front of magazine well
- improving ergonomics of shooting at marginal additional weight
- least protruding solution
- example picture; shaping should be integral with magazine well rather than an aftermarket solution, of course
- short stroke gas operated system
- no direct impingement to reduce need for cleaning, quite lightweight
- closed bolt operation
- necessary for sufficiently small dispersion out to respectable 200 m
- bolt catch; bolt remains in sprung position after last cartridge
- so the user immediately notices when the magazine is empty
- so the user doesn't need to repeat manually after changing the magazine
- larger tolerances than with infantry & scout assault rifles
- for reliability when dirty and lower costs, leading to a MOA (dispersion) of 2 or 2.5 (2.5 for air force and navy personnel other than guards)
- this should also reduce production costs
- suitable design and oil for reliable operation at -30°...+50°C operation at any humidity and the use of manually repeating weapon should be possible down to -40°C
- four seasons lubricant and four seasons cleaning oil
- no touching of metal parts necessary for combat use
- in case it's freezing cold and the user has no or only thin gloves
- good (nowadays ordinary) ease & quickness of assembly, cleaning and disassembly
- better odds of good-enough care even if the NCOs fail to enforce it
- for aiming just a cheap AAA battery-powered red dot sight on a NATO rail, flip switch for on/off (explanation later)
- red dot sight because this requires the least training and is the easiest to use under stress, a really cheap one suffices
- red dot suffices for effective range of 200 m due to flat bullet trajectory with this cartridge & barrel combination
- AAA instead of AA battery for less weight and bulk
- red dot size 2.5 MOA
- suitable for 200 m
- large and thus easy enough to see for close fights
- 2.5 MOA happens to be close to the dispersion MOA value of the gun
- sight line protected against smoke from hot barrel and possibly evaporating weapon oil
- trigger group with fire select trigger (single shot and either burst or full auto, depending on the armed service's preference - I would go for a 3...5 rds burst)
- mostly meant to make it easier for already terribly stressed users in close combat defence situation
- safety lever and all other interfaces in ambidextrous design
- ergonomics for right handers and left handers
- this includes symmetrical grip shapes
- ejection of spent cases can be changed between left and right by unit armourer, ideally without requiring spare parts
- ergonomics for right handers and left handers
- comfortable resting location for the index finger to promote safe behaviour (again ambidextrous)
- all interfaces and trigger guard designed with possible use of winter gloves in mind
- a short buffer spring
- so unlike with AR-15 design you may use fully folding shoulder stocks
- a fully top-folding stock, unfolding it should switch the sight light on and folding should switch it off
- example (for a shotgun) here. I understand this is not exactly top ergonomic, but it doubles as mechanically protective cover for the red dot sight
- minimizes the folded length (shorter than telescopic stock)
- narrower than side-folding stock
- it discourages the shooting while folded unlike the ergonomically similarly bad underfolding stocks, as it would obstruct the sight and would be very visible on top
- the stock would be angled when unfolded
- so the sight line is directly above the barrel and no bulky carry handle on top would be needed to raise the sight line as with a straight stock
- happens to reduce the silhouette when shooting aimed shots over a cover compared to straight stock weapons with their sights mounted high over the barrel
- no use of a sling, but multiple carrying solutions; the most relevant one would be a cushioned carrying on the back parallel to the spine with magazine well facing outwards (with a quick release interface!), ideally with other things (counterweights) worn on the other side of the spine such that you could even sit comfortably in a (vehicle) seat with the PDW on the back
- cleaning kit either stored in the primary hand grip or stored in the carrying interface
- no such thing as a forward assist
- marginal utility
- understood to be unnecessary in all rifle families but one
- compatible with all cartridges of the calibre at least with unit armourer-level adjustment of the gas operation
- steel parts gunmetal-finished, all other parts in a brown matte unicolour camouflage
- steel magazines
- cheap and durable
- I understand this is an exception from the rule to not need to touch metal in freezing temperatures
- unit-level armourer should be able to measure & replace magazine springs that were worn out
- availability of easy-to-use dry zeroing device on the small unit level
- important for maintaining zero and thus trust in the guns
Sadly, I do lack both the artistic talent and graphics software skills to illustrate such a PDW concept.
In the end, such a PDW would be more expensive than mass-produced assault rifles unless it is mass-produced itself as well. There's good reason why a PDW would be mass-produced; the vast majority of military personnel are neither infantry nor dismounted scouts. Those are a minority even in an infantry brigade.
One problem remains; non-combat and non-scout troops don't have much night fighting ability. Their NCOs may use flare guns for illumination and there may be some lights (essentially state of art of early WW2), but the expensive, fragile and scarce 3rd generation night vision devices and the thermal vision devices (which discharge batteries quickly) would be limited to infantry and scouts. The typical PDW user small unit is thus* at an even more pronounced disadvantage against infantry at night than at day. One could use cheap digital night vision with some illumination, but would that really be in stock for reservists throughout the 'lifetime' of a PDW (which could be 60 years)? Electronics don't last as long as guns, even when stored properly and separately from batteries.
And then there are other challenges for non-combat troops who need to defend themselves against infantry or scouts. In the end, nothing much more successful than a modest 'always carry' PDW with basic night vision will prevail due to the expenses involved.
S O
*: With PDW or an assault rifle like G36 or HK 416 doesn't matter - it's almost entirely about the night vision, training, mindset, organisation and the other weapons.
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For the most part (until the short buffer spring) you’re describing a Colt Commando with a piston instead of direct impingement.
ReplyDeleteSimple logistics considerations will make the Commando be preferable to any newly-developed system
Any thoughts as to extant systems which come closest to meeting your description eg short barrelled versions of current assault rifles - SCAR L CQC or SC? While I know many object to bullpups as a matter of principle, if we are talking about a PDW (as opposed to the infantry’s standard assault rifle) an ultra compact weapon such as the 330mm barrel Micro-Tavor might have certain advantages?
ReplyDeleteBullpup internal linkages and parts are difficult to keep clean and a right pain to get to if they are gummed up or contaminated. Conventional receiver designs are much more straightforward to keep clean and pry apart if you need to.
DeleteThere's footage from the Syrian war of a volunteer fighter stripping AK apart to beat out a broken spent case, and then picking out the shards from the action and the FCG. Embellishment aside, man suggested that he'd have died without the rifle's ramrod and leatherman that day.
I disagree that existing weapons come close.
ReplyDeleteCalibre and barrel length are common, but the ambidextrous features, emphasis on reliability when not treated well over performance, emphasis on extreme ease of use (and thus training) as well as the carrying concept are uncommon to nonexistent.
I suppose a decent gunsmith could develop the PDW I described based on the AR-18 system in a year or two with a budget of 500,000 €. It's not rocket science.
The issue is thus not whether similar weapons exist; the issue is whether any armed bureaucracy subscribes to approx. this PDW concept. My concept goes deeper than the mostly mechanical features; it's about an understanding what the weapon is for and what not, leading to a limitation of performance expectation in favour of comfort of carrying, and easy use with minimal (=ordinary!) training.
Milled or forged AR-18 and (aside from the ejection prot) AR-15/10 platforms are readily manufactured with ambidextrous fire controls, to the point that the most difficult part is milling out a cubic centimetre or two of the lower receiver to fit a ambidextrous bolt catch. Everything else is parts only.
DeleteAs for reliability, anti-tilt bolt carriers exist for piston AR-15s, and carrier tilt isn't usually a problem with AR-18s.
I'm curious about your framework for reliability: if you mention cleaning supplies carried with gun, then the AR should still be competitive with AK pattern weapons, and that would again be a point in favour of not having to develop a new gun.
A thing I missed re: ambidexterity: Even existing AR lowers can be milled out in a sufficiently well equipped armorers' shop. Realistically, an army will contract out to a manufacturer, but doing it in house *is* a possibility
DeleteI imagine this is for your concept of that conscript/cadre military reform, which is already a project requiring expenditure of much political and actual capital, so why not reduce a bit of friction by utilizing existing stocks of weapon from both a logistical and training standpoint?
Retraining the trainers is just as much of a pain in the ass./
One last thought as I finish my morning coffee; my impression is that the switch to the polymer magazine is precisely because they're equally durable and can be glanced at to see if it's dead, rather than having to troubleshoot bent magazines that need a close visual inspection. If it's cracked, it's toast, pull its replacement one out of your rucksack, scrawl some marker on the dead one, and go to your unit armorer when the action is all wrapped up.
DeleteOne could argue that FN aimed for this with the P90 in some respects (compact & easy to carry, modest range, ambidextrous). But it is clearly a very different design solution plus a bespoke & less capable calibre ….
ReplyDeleteThe P90 is astonishingly heavy given its calibre and the inferior cartridge would IMO be detrimental to the morale effect of the PDW.
DeleteI'm very Old School on this issue. Firstly: The small arms of an Army should only be two calibers: 9mm Parabellum for pistols & 7.62 Full Power for Rifles & GPMG's. This simplifies ammo supply and allows interchange between weapons when ammo gets low.
ReplyDeleteThe current system has 3 different calibers and is more complicated to supply.
ALL the PDW should use the pistol ammo. There should be 3 PDWs:
1) The pistol for Squad Leaders and Officers in "low threat" environments
2) The submachine gun for "high threat" environments & combat.
(The SMG could also be useful when issued to riflemen in "Close Combat" situations like Urban Warfare or Dense Jungle)
3) The carbine for all other support troops in the rear: Supply, Drivers, etc...
Why 9mm?
DeleteWhile the (hard) armor problem can be ignored at conventional war scales, since artillery and crew served weapons are the main casualty producer, almost *everyone* will be protected against 9mm.
Flatter shooting cartridges require less advanced knowledge of hold overs (and hold unders!). For a chest sized target, the difference in useable battlesight is 0 to 100m for 9mm vs 0 to 300m for multiple zeroings of 5.56.
This is of course useful for lower grade troops who recieve less training; I'd point also to the reported issues with 30 carbine in Korea: It wasn't shortcomings in terminal ballistics, it was mostly troops not aiming properly.
As for terminal effects, intermediate cartridges out of a 10-12" barrel carry double the muzzle energy of PCCs of the same length, and if you go to carbine or rifle lengths, triple. Forget about comparing them to pistol barrels. Even out of short barrels, older types of 5.56 still fragment reliably out to 100m at those velocities, and still very deadly out to say, 200m. EPR is even better for that, as well as capable of reliably perforating weaker types of hard armor.
As for SMGs, it should be telling that most forces have dropped pistol calibre weapons for even close protective work and other special purposes. It seems pretty clear that they're willing to accept tradeoffs in things like muzzle blast or controllability for the added power (and to be perfectly fair, blowback 9mm guns kick a hell of a lot even when compared to intermediate SBRs)
As it stands, the use case is for 9mm is for special operators to do morally dubious things when the cameras are off, and for officers to enforce discipline in the general retreat.
I'm not sure I understand the carrying concept. Is it something like a fully enclosed rifle case with backpack straps? A sort of rifle holster that clips over the trigger guard? How is the PDW deployed from the back to the front without a sling that can rotate around the body?
ReplyDeletePulling it with an arm from the own back should work. This might require a big release button to press with the thumb while the other fingers grab and pull at the handguard.
DeleteIt doesn't need to be enclosed, but there should be padding, the person should be able to bend forward and the CoG should be close to the spine so no or minimal counterweight is needed on the far side of the spine.
Even small carbines are usually not worn all the time, same with helmets. Holsters are worn all the time (if compatible with vehicle seating). Helmet, PDW and frag protection vest should be worn/carried at all (awake) times within 30 km of hostile artillery.
Is it kind of like a rifle scabbard?
DeleteA button that is large enough to press behind the back without looking would also be easy to accidentally press, I'd imagine.
Vehicles usually have rifle mounts which can hold rifles comfortably. I'd imagine there would be few cases of a crash or ambush serious enough to separate the pilot/driver from the vehicle.
For dismounted troops, modern quick-adjust 2-point slings allow weapons to be slung on the back quite securely, while also being able to deploy into action quickly.
Comfortable enough, not inhibiting work by bulk or mass, quickly detached for use.
DeleteThe exact design doesn't matter so much as the desired consequence; the soldiers should be armed 17 hrs per day.
Carbine mounts in motor vehicles don't qualify and slings don't, either.
Look at videos from Ukraine; rear area troops rarely have their helmet or gun on the body.
Hmmm, if we truly want to guarantee all-day carry, I think we might have to accept some serious compromises.
DeleteI carry a 5lb laptop in a backpack for work and even that I'd prefer to take off and leave at my feet if I could. Hard to imagine getting a loaded rifle-caliber carbine in a package more slim and lightweight than that.
Carrying a weapon 100% of the time even when the threat of attack is low is pretty much the exact use case of most civilians, and for that purpose a pistol (perhaps with a provision for a folding stock) is the only thing that has been proven to be lightweight and unobtrusive enough.
A pistol-armed soldier feels unarmed when facing assault rifle-armed stragglers. The challenge for a PDW design is to achieve all-time carry with the firepower to deal with straggler infantrymen and to deter hostile dismounted scouts from getting violent.
DeleteThe "comfortable" requirement is a bit softened by the fact that just the NCOs need to be fine carrying the gun at all times. Enlisted personnel would be compelled by the NCOs' authority.
I'm gonna call it the PDW Paradox: "If it's light enough for a personal weapon it's useless for a defense weapon".
DeleteBase's chef or plane crew with MP7 vs literally anyone with AKM? RIP.
Hence why this is a surprisingly difficult challenge for what is essentially a backup/morale weapon. Comments of "just put a folding stock on a carbine" overlook the ergonomic realities of actually carrying a heavy and bulky object 100% of the time. 3kg is just hard to ignore, especially if it juts out from the body and affects how you sit. Of course hikers carry more but they're not loading artillery shells or operating a vehicle at the same time.
DeletePractically I'd rather take the rifle caliber and just accept off-body carry as long as they are trained to not be more than three steps away from their rifle.
I'm more willing to spend the discomfort on wearing a helmet at all times rather than a helmet and a PDW. The armor is necessary to survive the ambush in the first place, while it will usually take a few seconds before you're able to effectively return fire if at all.
Sounds like a BRN-180 upper on surplus lowers with a pic rail stock adapter would work a treat
ReplyDeleteHi, A. A. here!
ReplyDeleteOTs-22 Buk with 9×19 DM91 AP
Sa 81 Krása with 7.62×39 BZ API
That's all.
Once you strip off the trade space it's another AR15. That's the cheap, proven, fiscally responsible battlefield-effective solution.
ReplyDeleteMp9/tp9/tmp in 9mm or 6.5cbj
ReplyDeleteA 3 lb machine pistol that can be hoisted and single handed. I expect saboted subcaliber ammunition to provide lighter recoil, and superior penetration to metal, possibly body armor, but worse in sand, brick and dirt.
As for the requirement for little training, that can't be done because training is the least costly and cumbersome defense.