Personal Defence Weapons:- Functional or Hype?

        PDWs or Personal Defence Weapons have become very trendy in military circles. What is worrying is that they are mainly being brought for roles for which they are totally inappropriate. The “stopping power” of the rounds used in these weapons is in many cases being grossly exaggerated and they have often been marketed as superior for close combat.

        The term “PDW”seems to have come into vogue around the mid-80s with the marketing of Heckler & Koch's MP5K-PDW, a version of the MP5K with a side-folding stock. The MP5K-PDW (or possibly the stockless MP5K) was worn by some helicopter crews in Grenada. With a 15 round magazine the weapon fitted a thigh holster and a pouch on the other leg could take five 30 round magazines or four 30 round mags and a suppressor.

        Around 1996 the meaning of PDW changed. Within NATO there was perceived a need for a compact defensive weapon to arm personnel who didn't or couldn't carry a full-size rifle but needed something more powerful than 9x19mm. It was felt Artillery, Signals, Transport and many other troops that did not perform assault missions needed self protection when performing normal tasks without burden of heavy weapon.

        Part of the specification that was to emerge in NATO Document AC/255-D/1177 (2nd Revise) was that it should be able to defeat CRISAT body armour at ranges of up to 200m. CRISAT was defined as a 1.6mm titanium plate backed by 20 layers of Kevlar. Light weight, low recoil and controllability were desirable. Since it was to be a “weapon of desperation”it was deemed acceptable for the PDW to use rounds other than NATO standard 9x19mm and 5.56x45mm.
        I refer to this new batch of weapons as “new-breed PDWs”, although Sven Ortman more descriptively calls them “Small Calibre High Velocity”or SCHV-PDW.
SCHV-PDWs

        One of the first weapons to appear that was intended to meet this specification was FN's 5.7x28mm P90. The P90 has several good features:- it is compact with good ergonomics, takes a 50 round magazine mounted unobtrusively along the top and ejects downwards, so is fully ambidextrous unlike many bullpups. It also looks futuristic and sexy and this, along with product placement in the TV show “Stargate SG-1”, an aggressive marketing campaign and camera time during the Lima hostage rescue has probably contributed to a few sales.

        The objectionable component of the P90 is its SS190 ammo. In order to meet the range and armour penetration criteria a light, pointed small calibre high-velocity round is used. FN have marketed this round as the replacement for the “obsolete” 9mm. They even produced a pistol using this round, the Five-seveN.

        Widely circulated in articles was the claim that the SS190 penetrates 5cm then tumbles and deposits all of its energy (495j/ 366.3ftlb) after 25cm penetration and creates a 8cm diameter cavity (the implication is that this is a permanent cavity). The 9mm FMJ, in comparison was claimed to exit after 30cm of penetration and only lose 97% (430j/ 318.2ftlb) and make a 3.5cm hole. Other Articles on the 5.7mm claim three times the stopping power of a 9x19mm.

        Even if the bullet was spinning like a buzzsaw it was unlikely to make a 8cm hole -the 5.7mm bullet can't be more than an inch long so to do this sort of permanent damage you'd need explosive expansion/fragmentation, which usually needs at least 2500fps of velocity -which this round is 200fps short of at the muzzle.
        Then I thought about the Control here -the 9mm FMJ round used for comparison. A 9mm FMJ that delivers 97% of its energy in 12”? -and makes a hole nearly an inch and a half in diameter doing it!

        If FN have a 9mm hardball that can do this in flesh they needn't bother developing the SS190 -armies and police departments will be queuing up all the way back to the Drelandspoint!
        Whatever gelatin these were shot against for these tests isn't a flesh analogue.

        At around this time I made the acquaintance of Bruce Jones who had extensively tested the P90 on behalf of the USMC. Bruce found that the stopping power of the 5.7mm was very poor and that in practice it was no better than a .22 Magnum. Tests by other agencies seem to confirm this finding and if we look at factors such as calibre and momentum this is not that surprising. Rounds that are smaller and have less momentum than the 9mm cannot to have more stopping power. Reports from actual combat use of the P90 seem to be rather mixed too, and I suspect that the successes were either from multiple or CNS (Central Nervous System) hits.

        This lack of stopping power is of particular concern since the P90 has also been marketed as a close combat weapon suitable for Police, Paramilitary and Special Forces. This is the area where most of the P90s sales have been made.
        This is probably the least suitable role for a weapon of the P90's characteristics but it appears certain departments and organizations have been swayed by hype and marketing. The USMC continues to state an interest in the P90 and MP7 despite the findings of their own R&D personnel.

        As a weapon for close range assault and defence the P90 and similar weapons are essentially “glass hammers”They are bold, innovative, lighter, high tech, modern etc…......but at the end of the day they can't do the job that is required of them. A weapon that inflicts ice-pick like wounds and has negliable stopping power cannot be considered suitable for personal defence.

        H&K were to produce their own “New-breed PDW” with the MP7. Many shooters seem to think that H&K can do no wrong but this is clearly a weapon that will not meet the shooter's real needs. The MP7 itself is more conventional than the P90, externally resembling an Uzi-type SMG with cosmetic work. At 13.4” long it is bulkier than one might expect and weight is close to that of some larger-calibre machine pistols. The 4.6x30mm round used appears to be very similar to the 5.7mm both in design philosophy and performance. Being lighter and smaller it is if anything potentially even less effective for close combat than the 5.8x28mm. The German KSK commando unit has brought a few, as have some police forces. It seems good marketing can usually beat science

        There have been a few other contenders for new PDW rounds. Leitner-Wise LW15S and .224 BOZ both use rounds using the proven 5.56mm rifle bullet mounted in a 10mm Auto case. The .224 BOZ mounts the round conventionally in the 10mm Auto case while the Leitner-Wise round uses a 7.82mm barrel and a discarding sabot. How useful these rounds are will depend on the muzzle velocities achieved. The 5.56mm bullet relies on fragmentation for a lot of its terminal effects, and this does not occur at velocities of less than 2,500-2,700fps. If these rounds do not reach these velocities then there is little point in using them instead of very short barreled 5.56x45mm weapons.
        It would have been more useful if Leitner-Wise had retained a 10mm barrel on their weapon or based it on a .45 so it could use both saboted and full-calibre rounds. However, then they would be in the business of selling just ammo and not guns.
        The .224 BOZ is also available in a handgun with velocities of 1,750-2,200fps being quoted. These give a TKO of around 3.5. Like the Five seveN a pistol with high penetration but low stopping power may have applications, but it is debatable if it can be called a defensive or personal protection weapon.

        The most interesting approach is by the Swedish company of Saab Bofors (right) which mounts a 6.5x25mm bullet in a round with the same overall dimensions as the 9x19mm NATO casing. Sven's page gives the impression that this is a discarding-sabot round but I find no mention of this feature in Jane's Infantry Weapons. It's possible that as german is his first language Sven doesn't appreciate that “sabot” can in some contexts means “outer layer”.
        The 31gr bullet consists of a tungsten alloy core surrounded by plastic and muzzle velocity is claimed at 2,673fps (815m/s) from a barrel of about 7”. This compares very favourably with the P90's 2,345fps (715m/s) from a 10” barrel or the MP7's 2,378fps (725m/s) from a 7” barrel. TKO for this round works out as 3 and since it appears to be a round-nosed pistol type round it is unlikely to show any tumbling. Terminal effects may also be lower if just the lighter and smaller tungsten core only penetrates armour. TKO values for the 4.6mm and 5.7mm are given here and it can be seen that the 6.5mm is a shade better than these rounds unless tumbling occurs, which is never certain.
        Saab Bofors claims the 6.5mm CBJ has a combat range of up to 400m and is effective against light armoured vehicles such as APCs. Although the HK and FN rounds are spire-pointed while the CBJ appears to be round-nosed the Swedish round seems to retain more down-range velocity. Velocity at 200m is given as 2,072fps (632m/s) and 1,535fps (468m/s) at 400m. The published figures for the 5.8x28mm with a 31gr bullet (the same weight as the CBJ) is 2,134fps at 150m and 1,291fps at 400m. The 4.6x30mm claims only 1,771fps (540m/s) at 100m and uses a lighter (24.7gr) bullet. The CBJ therefore appears superior in down-range velocity, energy, momentum and calibre.

        The construction of the 6.5mm CBJ bullet is the same as the APCR rounds I've suggested for use in the 9mm pistol. A bottle-necked cartridge based on the 9mm is similar to the proposal of Stan Crist, although this has been tried before with rounds such as that for the SCAMP. The weapon designed for the 6.5mm is the CBJ-MS, which resembles the Mini-Uzi and includes a storage for an additional magazine in the forward grip. Theoretically many other 9x19mm SMGs can be adapted to fire the round just by changing the barrel.

Update
        Dino Snider found this discussion and photos that indicate that the CBJ round is a discarding-sabot design using a 4mm bullet. I really find it hard to believe any 4mm bullet, no matter how fast, produces a “large deep cavity?”. A 5.56x45mm 62gr bulllet is a poor performerder at under 2700fps. A 4mm round of half the weight at the same velocity is unlikely to be as effective.


        Let us re-examine the premise upon which the new-breed PDWs were designed, that of a weapon for defense of troops that cannot carry rifles and perform their normal duties.

        If we accept the premise that troops do need a compact wearable weapon that can protect them from enemy infantry we need to realistically consider what this weapon needs to do. Being able to kill or injure an enemy would be desirable, but we may realistically have to settle for simply spoiling his aim or forcing him to take cover rather than shoot. To achieve this the rounds must land close to the enemy and give the impression they will do serious damage if they connect. The Mauser 712 Westinger Schnellfeuer pistol was noted as being an intimidating weapon to come under fire from, having a high rate of fire and using a high velocity bullet. A version of this is still made as the NORINCO Type 80. The idea of a 7.63x25mm PDW has some merit, since 7.63mm Mauser/7.62mm Tokarev is by no means an uncommon round and would be even more effective with a composite bullet like that of the CBJ. A typical 7.63mm round is 86gr at 1,400fps (1,700fps for vz52 ammo).
        To my mind the P90, MP7 and CBJ-MS are all too large. The first two are also possibly too expensive for wide scale issue. It would be more convenient to have a weapon that can comfortably be carried in a holster. Of the rounds available, I think the best for this role is the 6.5mm CBJ fired from a compact machine pistol such as the Skorpion, Ingram/Cobray, South African BXP, ROMBARM BORD, Russian OTs-22, Hungarian Voros, MGP-84, Micro-Uzi/Mini-Ero, Steyr TMP etc.
        Since the weapon should be capable of being easily carried in a holster I'd prefer a weapon with a magazine that inserts into the grip. A straight magazine would also avoid confusion with those loaded with 9x19mm, such as are used for the MP5. A folding or retractable stock and a folding foregrip would be good features, as would a compensator. It would be useful if the spare magazine pouch also had provision to carry a smoke grenade.
        I'd prefer not to base this weapon on a pistol, since this would create the impression that it is a weapon suitable for close combat. A machine pistol would probably be easier and cheaper to manufacture.
        This would be a weapon for breaking contact rather than a close combat weapon. If forced to use the weapon at close range in an emergency then controllable automatic fire will compensate partially for the low stopping power of the individual rounds.

        Some companies are offering short barreled versions of 5.56mm assault rifles as PDWs. When fired from short barrels (14.5” or less) the terminal effects of the 5.56x45mm FMJ round is greatly reduced though such rounds may serve for suppressive fire. Problem with shorty assault rifles for the PDW role is that they are not much smaller than full-size weapons but considerably less effective. For just a few inches more overall length you could have full rifle performance. The heavier, higher sectional density bullets proposed for rounds such as the 6.5mm Grendel, 6.8mm SPC and 6.5mm MPC will be less velocity dependent than the 5.56mm for their lethality and may work better in shorter barreled weapons.
        There is probably a niche for very lightweight rifles for troops who have to carry their weapons more than they use them. The Carbon-15 series weapons use carbon-fibre receiver halves to create 16” barreled weapons of around 4lbs weight, ideal for recon troops and heavy weapon crews. Retail cost of the Carbon-15 is about the same as a conventional AR-15.
        I think too much emphasis has been placed on having a short weapon for a PDW. The most successful weapon to fill this niche has been the M1 carbine. This had an 18” barrel and was 35˝” long. This suggest that more desirable features for such a weapon are light weight and low bulk. Interestingly both the M1 Carbine and P90 are of around 2.5kg (5˝lb) weight. Prior to the pointless Brady Bill some civilian shooters discovered that folding stocked versions of M1 Carbine such as the M1A1 are very handy packages to carry when walking around the ranch or similar tasks.
        It should be possible to design and issue a “Lightweight Defence Carbine” (LDC) for the protection of the sort of troops that the PDW was supposed to arm. Desirable features would include:-         Numerous weapons nearly fit these requirements.
        The Kel-tech SU-16 (below, left) is a folding rifle that uses M16 type magazines. A simpler foregrip will probably reduce the weight a bit more.

SOF on the SU-16
SU-16Floro PDW

        The Philippino Floro International “PDW” (above, right) looks a little like a hybrid of the Colt Commando and Thompson SMG with a M1A1 Carbine stock. It weighs 2.9kg with an 8” barrel. With the barrel extended 6.½” this might be a very useful weapon.

        Another weapon, the American Arms Tech Compak 16 weighs 2.5kg with a ca 10” barrel. This uses a standard M16 lower receiver with a M231 Firing Port Weapon type telescopic wire stock. All this design really needs is a longer barrel and deletion of unneeded features such as the full-auto capability and Picantinny rail.

        Since I first wrote this article Kel-tech have produced the Delta (left), a version geared more towards the military PDW role.
        They claim the SU-16D9 is less than 20” folded, weighs 4.7 lbs loaded with 30 rounds and has a practical range of over 300m. The D12 weights about 4.8lbs and would be under 24”. With a 14½ barrel this weapon should be ideal as a defensive carbine.

        The size of a rifle is always going to make them unsuitable for certain roles, however.
        Some of the other proposed PDWs have been short rifles using novel rounds, essentially trying to reinvent the M1 Carbine. While the M1 Carbine was a considerably lighter and less bulky weapon than the .30-06 Garand these modern designs offer only a small saving over modern 5.56x45mm assault rifles -certainly not enough to justify the complication of an additional ammunition type.

SubCarbines

        As we have seen above and elsewhere, the stopping power of the new-breed PDW rounds is considerably inferior to that of the “traditional” pistol rounds. For CQB operations Police, Special Forces, Paramilitaries and any other users are better advised to select 9mm or preferably .45 weapons. A compact machine pistol with a double action mechanism may be more useful for special operations. Conventional pistol rounds are also more suited to use with suppressed weapon. If body armour is a concern then a mixed magazine of JHP or Flat-nose rounds and APCR or APDS rounds can be used. APCR, essentially a full calibre version of the 6.5x25mm CDJ is a concept that deserves to see wider use in 9mm and .45 weapons. Such rounds offer high penetration while still allowing the use of a suppressor. Discarding Sabot rounds may utilize smaller calibre rifle bullets, heavy flechettes or some intermediate form of projectile.
        A compact weapon firing high penetration ammo with very little stopping power may have applications for special forces, although such applications are likely to be very specialized, and close quarters combat is not one of them. A good argument can be made that this niche is better filled by short-barreled 5.56mm weapons, which includes pistols such as PLR-16 (left) and Olympic Arms OA93.

        Another mission that has been suggested for PDWs is as an armament for tank and AFV crews. Despite the potent armament of such vehicles the “dead zone”close to the vehicle means that tankers have often had to resort to weapons such as .45 pistols to defend against infantry attack. This is another situation where “knockdown power” is more important than long range or armour penetration.
        In this article I've suggested that a .45 machine pistol would be a very useful weapon for vehicle crews This weapon may be the same “close assault MP” described in the paragraph above. This is a distinct tactical niche different to that proposed for the PDW. When dismounted vehicle crews can use folding stocked assault rifles. Many tank crews in Iraq have adopted AKMs due to a shortage of M4s.

        There is an adage somewhere that it is wiser to improve the ammo than create a new weapon. Discarding sabot ammo has seen very little use in handguns and machine pistols, though there is no real reason why this should be the case. Use of a discarding sabot increases the velocity of a round, which gives a flatter trajectory, more penetration and shorter flight time. It is possible that such ammo properly developed in pistol calibres may allow existing weapons to at least partially meet the requirements suggested for a PDW.


        In his introduction to Jane's Infantry Weapons 1989-90 Ian V Hogg discusses the then new concept of PDWs. He observes that they are intended to fill a similar niche to that for which the M1 carbine designed. He comments that the main problem with the M1 carbine was that it was often mistaken for a rifle and used for front line combat. He comments that this is unlikely to be a problem with the new PDWs.
        Ironically the problem with modern PDWs is that they are mistaken for SMGs.

Ref.
        Sven Ortman's webpages on PDWs. Also has information on various other “special application” weapons such as selective-fire handguns, compact machine pistols and high penetration pistols.
http://www.personaldefenceweapons.com


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