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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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Lawman       12/2/2007 11:09:23 AM
Huh?
 
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Horsesoldier       12/2/2007 12:52:31 PM

The best PDW so far must be this: http://www.defensereview.com/modules.php?name=News&file=article&sid=1011AS" target=_blank>link for the 6x35vs 5.56x45... Why not take the best of two worlds: 6x45,44 or 43 (for higher BC bullets..)

6x45 wouldn't really be a PDW specific load anymore, but (depending on format) would be workable as a general purpose sort of round, without a doubt.  Something in an 80-90 grain load would be good, though the case would have to be something with a little bit more capacity than a .223 cartridge, in my opinion, just to keep a good velocity.  Even with 77 grain Mk 262 you're getting a lot more bullet drop at range than with 62 grain 5.56mm -- I like the better bullet weight, but would not mind getting a flatter trajectory in the bargain as well.
There is a guy over on The High Road who has done up the specs for a number of wildcat cartridges based off of the old Czech 7.62x45 cartridge that look like they'd have potential, for those interested in additional reading on the topic.  I believe he's in the process of actually generating loaded ammo and trying it out on a couple of those loads.  (That's also the case that Gary Roberts and others have based their 7x46 Optimal assault rifle round off of, though that one is kind of burly to be an "intermediate".)
 
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flamingknives       12/2/2007 2:09:19 PM
As I see it, a PDW is a funky new abbreviation for a sidearm. Don't compare them to rifles, but to pistols, and it all makes more sense, and the MP7 makes more sense than the rest.
 
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dobrodan       12/2/2007 2:40:29 PM



The best PDW so far must be this:  ="" modules.php?name="News&file=article&sid=1011AS""" target="_blank">link target=_blank>link for the 6x35vs 5.56x45... Why not take the best of two worlds: 6x45,44 or 43 (for higher BC bullets..)


6x45 wouldn't really be a PDW specific load anymore, but (depending on format) would be workable as a general purpose sort of round, without a doubt.  Something in an 80-90 grain load would be good, though the case would have to be something with a little bit more capacity than a .223 cartridge, in my opinion, just to keep a good velocity.  Even with 77 grain Mk 262 you're getting a lot more bullet drop at range than with 62 grain 5.56mm -- I like the better bullet weight, but would not mind getting a flatter trajectory in the bargain as well.

There is a guy over on The High Road who has done up the specs for a number of wildcat cartridges based off of the old Czech 7.62x45 cartridge that look like they'd have potential, for those interested in additional reading on the topic.  I believe he's in the process of actually generating loaded ammo and trying it out on a couple of those loads.  (That's also the case that Gary Roberts and others have based their 7x46 Optimal assault rifle round off of, though that one is kind of burly to be an "intermediate".)


As even the 6x35 round is too long for a pistol-type weapon, a 6x45 could just as well be used, especially in a bullpup-weapon. It could also be used as a general purpose round. Because of the larger bore-diameter, and similar volume to the 5.56, it could (and should) be optimized for shorter barrel-lengths (14,5" should be sufficient.)

Also, with mk262, you get less bullet drop at long ranges. Comparable with 7.62 NATO, actually... With a 6mm with a respectable BC and relatively light weight, you should get a quite flat trajectory, even out of a short barrel.

also, if the 5.56-brass has too small capacity, you could always "7.62x45-iate" some 5.45x39 brass... Making it 5.45x43, and start from there...

While I´m sure the 7x46 is an excellent round, I feel it is a bit too heavy for replacing 5.56... 

I believe slightly up from 5.56 would be the way to go... Give it a little more reach, a little more energy, and optimize it for shorter barrels than 20"...
 
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WarNerd       12/2/2007 4:27:10 PM
 
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Horsesoldier       12/2/2007 10:21:12 PM
Also, with mk262, you get less bullet drop at long ranges. Comparable with 7.62 NATO, actually... With a 6mm with a respectable BC and relatively light weight, you should get a quite flat trajectory, even out of a short barrel.
 
Mk 262 has more drop than 62 grain M855.  With my ACOG (with 5.56mm reticle) I have to hold high when shooting 77 grain -- about shoulder level at 400, top of the head at 600, seems to get consistent hits on steel chest plates when factoring in barrel length as well.  77 grain is close enough to 7.62x51 150 grain trajectory that you could use an ACOG with a reticle for M80 ball ammo, though, without having to make much, if any, adjustments.
 
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Horsesoldier       12/2/2007 10:25:22 PM

As I see it, a PDW is a funky new abbreviation for a sidearm. Don't compare them to rifles, but to pistols, and it all makes more sense, and the MP7 makes more sense than the rest.

There seem to be definitions of the term ranging from handgun to SMG and up to the "classic PDW" M1/M2 carbine.  I think there's probably two real roles there, basically -- something in the compact machine pistol/SMG category replacing the pistol, and something more like the M1 carbine, which is currently done by things like the M4 carbine.
 
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Horsesoldier       12/2/2007 10:32:19 PM

 

Thats a non-starter.  It would be a logistical nightmare, not for ammunition but for spare parts.
 
While I'd love to be able to carry my preferred hand gun(s) in a combat zone, the logistics really would be bad.  Besides spare parts, magazines would be a nightmare even if you had an approved list of, say, a half-dozen handguns or something like a lot of law enforcement agencies do.


 
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WarNerd       12/3/2007 4:41:39 AM
From what I can determine from the literature, a PDW is supposed to be:
 
>   Have greater effective range than a pistol.
>   Be compact enough to be easy to fired from confined spaces (i.e. from within a vehicle)
>   Capable of penetrating body armor at a reasonable range (>100m?). 
>   Light enough, and small enough when not deployed (for folding designs), that it can be worn by vehicle crews at all times.  This is so that if they have to bail out they will be effectively(?) armed.  The assumption also is that they cannot afford the time to collect weapons before they exit the vehicle.
 
Needless to say, meeting all these requirements, especially the last will be 'difficult'.
 
>>   The PDW will probably be a replacement for the submachine gun.  The PDW is not is a assault rifle replacement.
 
 
 
 
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MadMilitaryMind    PDW go back to the .45   12/3/2007 4:46:05 AM
While I agree that PDW is to broad a term, my vote is to forget the the H&K MP7 in its 4.6x30mm:
and the FN P90 in its 5.7x28mm. the rounds are just to small I say go back to the .45 ACP
The Kriss looks like a steep in the right direction, though clip size is abit of an issue it looks to make that up with its controllability

http://world.guns.ru/smg/kriss1.jpg">
http://world.guns.ru/smg/smg96-e.htm
 
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