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Subject: someone asked for a 6mm? (will you take that in a PDW?)
doggtag    11/30/2007 8:14:08 PM
Been digging around... Have we ever gotten into a PDW (Personal Defense Weapon) debate on here? Some people are still old school and consider personal defense to be either pistols (clip-fed semiautomatics or revolver handguns) or submachine guns. But most of us here have at some point heard of the two most commonly known, dedicated PDWs, the H&K MP7 in its 4.6x30mm: ht*p://www.hkpro.com/pdw.htm and the FN P90 in its 5.7x28mm: ht*p://world.guns.ru/smg/smg13-e.htm (There are plenty more sites available with a proper search, many certainly biased toward one or the other depending on fanboydom, but still it shouldn't be hard to compare the pluses and minuses of each.) Recently, I also came across this one, the Knight's Armament Company 6x35mm PDW: ht*p://www.knightarmco.com/images/pdw1.html (a random search thru SP's archives suggests we've never discussed this weapon before.) What's interesting with this one is, it's borderline on being a direct challenger to carbines in 5.56mm caliber, with a 10inch barrel giving it a 300m lethal range, which certainly outranges the nominal 200m lethality ranges of which both the MP7 and P90 were developed with in mind. What's interesting with the 6x35 is, at least according to the article/ad from KAC, is that it slightly outpaces (in ft/lbs) the 5.56 at 300m from a slightly shorter cartridge case. One wonders what might come of it were it a "full length" case, equal overall to the 5.56 NATO standard. But then again, fanboys of the 5.56 would decree there's no phenomenal increase over 5.56, just as they have done with every other sub-7.62x51 contender, so it warrants no further discussion. What exactly warrants the ideal performance increase then, if we want more oomph (range, penetrability, and lethality) over 5.56 but still refuse to accept the weight/bulk penalties of carrying heavier 7.62? And what I'd like to know is, how would the 6x35 from a longer barrel (12"? 14"?) compare to 5.56 from a similar-length barrel? If the M4 is the wave of the future for the 5.56mm round, until someone comes up with that phenomenal replacement (rail gun, particle beam weapon, phaser gun,..?), if 300m and shorter ranges (CQB) are to become the norm of the next few decades, would we be further off pursuing a round more tailored to actually perform more ideally at these ranges (up to 300m), than a round which was, at least when I went to Basic in 1990, designed with a maximum effective range (from a 16&1/2" barrel) of 460m, (so we were told) ? What's even more interesting there is, every US Army M16 qual range I've ever been to, no target was representative of an adversary farther away than the 300m mark. If lighter and more compact carbines are the (supposedly) preferred choice of the latest generation of US infantry, then is a purpose-built PDW-type weapon (more compact & lighter than an AR) the more logical course of action, as opposed to keeping with the status quo's current 5.56 who, regardless of credibilities on behalf of its naysayers, obviously has been brought under scrutiny more times than a person can count, and certainly will be until its withdrawal from service ? Thoughts?
 
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doggtag       11/30/2007 8:17:18 PM
 
http://world.guns.ru/smg/smg13-e.htm   FN P90 personal defense weapon / submachine gun
 
 
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Horsesoldier       12/1/2007 1:05:44 AM
The KAC round is the most promising of the three major PDW rounds out there these days, though I think it will be the least successful in the long run simply because FN and HK swing a lot more $$$ weight than Knights.  I don't know of anyone who is actually using the thing
 
And what I'd like to know is, how would the 6x35 from a longer barrel (12"? 14"?) compare to 5.56 from a similar-length barrel?
 
Not sure, but my guess is that performance advantage gets less impressive for the 6x35, and probably ultimately loses out to 5.56mm as you go longer on barrel length.  A 6mm 65 grain projectile is going to have a lower ballistic coefficient than 62 grain 5.56mm, so my guess is that they're clocking better numbers from a 10" barrel by using faster burning powder to get better utilization of the charge in the case.  If this is the case, it probably gains less from an extra few inches of barrel than 5.56mm would.  The claim of lower recoil impulse compared to 5.56mm/10" barrel is a pretty solid clue that 6x35 is doing max effort or close to it with a 10" barrel, while 5.56mm is putting a lot of unburned/burning powder out there in the muzzle flash.

But then again, fanboys of the 5.56 would decree there's no phenomenal increase over 5.56, just as they have done with every other sub-7.62x51 contender, so it warrants no further discussion.
 
It's an interesting round, but you have described why it probably won't find any major success as a military weapon, or with contractors working in the war zone -- short barrel M4s work pretty well, and can be made to work better with non-USGI compensators and such fitted, and provide logistics commonality. 
 
My guess would be that it will primarily take off only if it finds some success with law enforcement entry teams and such, or on the very off chance that one of the major contracting companies decides to adopt it.
 
if 300m and shorter ranges (CQB) are to become the norm of the next few decades,
 
They always have been.  It's simply the limits of guys with iron sights engaging point targets with any degree of effectiveness.
 
What's even more interesting there is, every US Army M16 qual range I've ever been to, no target was representative of an adversary farther away than the 300m mark.
I suspect this might change at some point now that ACOGs are pretty heavily issued.  Guys in the DMR role are shooting at longer range targets on shooting tables specific to that job.  If we get something like the Elcan Spectre (x1 or x4 at flip of a lever) issued heavily in the Big Army it's probably reasonable to expect qual standards (at least for guys with that optic) to go out to 500 or 600 meters . . .
 
. . . assuming the army cares to spend the money to revamp all the qual ranges out there, after spending the $$$ on the optics themselves.
 
If lighter and more compact carbines are the (supposedly) preferred choice of the latest generation of US infantry, then is a purpose-built PDW-type weapon (more compact & lighter than an AR) the more logical course of action, as opposed to keeping with the status quo's current 5.56 who, regardless of credibilities on behalf of its naysayers, obviously has been brought under scrutiny more times than a person can count, and certainly will be until its withdrawal from service ?

I don't see how 6mm 65 grains is going to do much in terms of terminal ballistics that 5.56mm 62 or 77 grain won't do already.  I don't see much evidence that 5.56mm has been brought under scrutiny by people who are overly informed on the subject matter, but regardless, I doubt 6x35 would answer any of the critics' complaints about 5.56mm.
 
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flamingknives       12/1/2007 5:07:57 AM
What benefits would you get from that as opposed to an M4 carbine?


 
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Horsesoldier       12/1/2007 11:19:09 AM

What benefits would you get from that as opposed to an M4 carbine?




It is supposed to be more controllable at very short barrel lengths (8" and 10" is what they are making), and deliver somewhat better ballistics in those packages.  It looks like, shooting a lower energy round, allows them to also use a more compact receiver and therefore get a smaller, more compact weapon overall.  A final strength (and why the avoided the more length efficient bullpup format, I'm guessing) is that it looks like it basically replicates the M4 manual of arms with control layout.  The lack of an adjustable LOP stock might be a downside, though it looks like they picked a LOP well suited to CQB shooting.
 
I'd be curious if it would be possible to make loads for 5.56mm optimized for the short barrel lengths in question that do the same thing.  I'm not sure if the pressure levels in the 5.56mm case would not be doing something wonky (either dangerous, or troubling for reliable function, or raising issues if you wanted to go back to shooting standard ammo) if the round were re-configured for faster combustion, though.
 
 
 
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WarNerd       12/1/2007 1:42:46 PM
The problem here I think lies in the definition of a PDW (Personal Defense Weapon).  And the problem is that an official definition simply does not exist.  In this absence, anything can be called a PDW and we end up arguing apples and oranges.
 
Look at the 3 weapons under discussion, the Knight's Armament Company 6x35mm PDW is an M-4 class assault carbine, the FN P90 (4.6x30mm) is a submachine gun with an unusual magazine system, and the H&K MP7 (4.6x30mm) is almost a machine pistol.  The only thing that they have in common is that each uses a cartridge that is unique to that particular weapon.
 
The definition of a PDW seems to be that it is a weapon for personnel who do not plan to use it and are only minimally qualified, but are likely to be in a situation where they need an effective combat weapon.  In other words, just about everyone in the military that is not infantry or SOF.
 
So, new question: 
1.)   What weapon would you want strapped to you when bailing out of your tank?
2.)   What weapon would you want strapped to you when bailing out of your supply truck?
3.)   If not the same, why not?
 
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Horsesoldier       12/1/2007 2:32:44 PM

The problem here I think lies in the definition of a PDW (Personal Defense Weapon).  And the problem is that an official definition simply does not exist.  In this absence, anything can be called a PDW and we end up arguing apples and oranges.
 

I think another issue with the PDW idea is that I feel like it is rooted in somewhere around 1980s technology and a 1980s Cold War mentality.  The basic premise for their wholesale issue is that support personnel don't need to use their weapons frequently, and that a conventional rifle of M16 or larger dimensions is an impediment,  The first half is true, unless they're running convoys in a low-intensity warfare setting, operating on a conventional but fluid battlefield like we saw with the invasion of Iraq, etc.  The second half is a valid observation, though it becomes less valid when we're talking about things like M4s and bullpup assault rifles, I think.
I don't really like the idea of being a non-combat sort of person who is then handed a weapon that screams to any bad guy attentive enough to notice "non-shooter here."  If I'm an insurgent, I'm already wanting to target guys who aren't trained trigger pullers to begin with instead of combat arms units that will likely come at me with a lot of well-focused combat power. 
 
The logistical dimension is another problem, I think, as well.  The typical western mix of 5.56mm and 7.62x51 seems to work pretty well, and I don't think you get much real improvement from adding a third cartridge to that.  Whether or not 5.56mm is the ideal round is another issue, but I personally think that if we're looking at a replacement for it the right answer is to go heavier (either working out a maxed out 5.56mm round in something like the 90 grain bullet weight, or something in the general vicinity of 6.8 Rem SPC and 6.5 Grendel).  The KAC 6x35 round might be heavy enough for consideration as a general service cartridge (though I suspect it is actually a little anemic for that), but FN 5.7 or HK 4.6 are definitely going in the wrong direction for general issue.

 
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dobrodan       12/1/2007 3:02:46 PM
The best PDW so far must be this: http://www.defensereview.com/modules.php?name=News&file=article&sid=1011AS for the 6x35vs 5.56x45... Why not take the best of two worlds: 6x45,44 or 43 (for higher BC bullets..)
 
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Lawman       12/1/2007 3:14:00 PM
On the issue of PDWs, I do like them, but they are pretty specialised weapons - a pistol will do in a pinch, and a carbine will generally do for close quarters. They do bring to the table their compact firepower, but to be honest, the M4s do pretty much the same thing anyway, and despite all the negative press to the contrary, actually do the job pretty darned well. One thing I would be interested in would be one of the modular weapons systems, whereby an M4 type rifle can use a variety of barrel lengths, depending on the situation (e.g. 12in for close quarters, 16 for most purposes, and even 20in for longer range work, like Afghanistan).
 
As for the inclusion of optics on standard service rifles, the SUSAT on the L85 had a major effect on weapons quals in the UK, since pretty much anyone was able to hit figure of eight targets at pretty decent ranges. This has a massive effect on the general accuracy of all the troops. One question is whether or not to make it a standard issue item, or to make it an option, up to the troops, which has obvious advantages (cost is the obvious one, but it also allows newer optics to be bought as they become available). I would argue in favour of just allowing the troops a certain degree of latitude on attachments, so that troops can buy whatever the unit commander approves, as long as it fits within the regulations.
 
This could potentially be extended to sidearms, allowing the troops to buy any approved type, as long as it fires one of the two approved calibres (.45 or 9mm). This would be cheaper than making them standard issue, and to be honest, how many troops would decide not to buy at least a reasonable sidearm, given the choice - they would obviously still be subject to restrictions, as decided by their unit commander. This logistics issues aren't all that bad, since the ammunition would all be standard, and it is only for the sidearms.
 
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Yimmy       12/2/2007 9:02:02 AM

This could potentially be extended to sidearms, allowing the troops to buy any approved type, as long as it fires one of the two approved calibres (.45 or 9mm). This would be cheaper than making them standard issue, and to be honest, how many troops would decide not to buy at least a reasonable sidearm, given the choice - they would obviously still be subject to restrictions, as decided by their unit commander. This logistics issues aren't all that bad, since the ammunition would all be standard, and it is only for the sidearms.

Thats a non-starter.  It would be a logistical nightmare, not for ammunition but for spare parts.
I don't think there is a military application for the new PDW's, I think they are rather a product looking for a requirement.  5.56mmsub-carbines such as the H&K53 are as small as anyone could possibly want to go - why would you want something smaller and lighter than that?  Are we all shrinking into weak pixies with girly petite hands or something?  After a point weapons become awkward and flimsy when they shrink too much.

 
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Yimmy       12/2/2007 9:03:25 AM
I forgot to add - handguns are gay.
 
 
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