schnuersi said:

The 7,5 BRNO has been my counterargument that this means a 5,56 SBR is needed. The 7, BRNO delivers the same level of performance at 100 m and can be used form a weapon of the same size and layout as the MP7 or MP9. This a true PDW is still possible and an SBR which would require the additional issue of handguns not necessary. There also is a noticable tendency to turn a PDW into a general issue short range assault weapon... which of course leads to the conclusion that 5,56 carbines are the way to go. This IMHO is on the focus of the needs of infantry at the detriment of all other personell.

I agree. MP9ish kind of gun in 7.5FK and call it good. No mission creep towards LW assault rifle for SF or similar. For that I'd do something like a honeybadger (bullpup?) with integral suppression in .300 BLK subsonic.

graylion said:

       schnuersi said: The 7,5 BRNO has been my counterargument that this means a 5,56 SBR is needed. The 7, BRNO delivers the same level of performance at 100 m and can be used form a weapon of the same size and layout as the MP7 or MP9.

I agree. MP9ish kind of gun in 7.5FK and call it good.

Before we can call it good, you first need to convince a manufacturer to actually develop and produce an MP7/MP9-ish kind of gun in 7.5 FK.

Unless/until that happens, 7.5 FK is not a real option.  It is only an imaginary counterargument to a 5.56 (or .300 BLK) SBR for use as a PDW.

Aka the same problem that keeps my beloved updated Colt scamp from being a viable option...

On the plus side though the diy gun community is slightly reducing this problem by putting together at least decent stand in's at a much quicker pace than in previous years.

Granted these diy range toys aren't suitable themselves but at least give us an idea of how a factory built gun could perform.

My hope is that eventually some of the more talented diy guys will put together a neo scamp 2.0 and other things for us to start playing with and see if they may actually be viable.

Not sure what "diy range toys" you're talking about, but it sounds like they might be comparable to concept demonstrators developed to pitch an idea to the military.

If that is the case, it seems like they would be perfectly fine for informal test and evaluation.

stancrist said:

It is only an imaginary counterargument to a 5.56 (or .300 BLK) SBR for use as a PDW.

It is a hypothetical argumnet yes.
It falsifies the argument that 5,56 is needed because if the ME. Because if the 7,5FK can do it others could as well.

I am not convinced that 7,5FK is the ideal or even a good choice. Its just a cartidge that has some properties and a size that make it comparable and data for it is available.

schnuersi said:

It falsifies the argument that 5,56 is needed because if the ME. Because if the 7,5FK can do it others could as well.

I think that those who argue for 5.56 do so based on the weapons that actually exist.

Below:  M16 variant in 5.56 NATO

Below:  MP7 variant in 7.5 FK 

Sig Sauer ended the PDW search by delivering a 5.56 ot 300BLK gun in package sized like MP7

Mr. T (MrT4) said:

Sig Sauer ended the PDW search...

That seems doubtful.  AFAIK, the Australian Defence Force is the only army to adopt the Sig MCX Rattler as a PDW, and it's not clear if the ADF intends it to be a general-issue PDW or a special purpose weapon just for SF and MP use.

I have faith in Saint George of Kel-Tec.

We also argue for them based on 5.56 weighing less round per round than even 9x19 which is sorta one of those paradoxes we're fighting here.

It's sorta hard to justify carrying less rounds that are less capable at about the same or more weight.

Like my foxtrot Mike 11.5 weighs 5 pounds naked and isn't much more than 6 fully dressed and can punch 3a armor and give you rifle round killing power out to at least akm effective range (which any noob with some proper basic instruction can use to it's fullest potential pretty quickly after a couple flat range sessions)

In a military setting do I really want to give any of that up to save maybe a couple pounds of weapon weight?

Especially since I can with proper sling setup and a belt mounted slung weapon catch conceal my stockless 11.5 under a coat!

And again I'll emphasize the whole "with rifle projectile killing power out to basically 300 meters" thing because even with my civilian 68 grain bthp match loads I have almost mk318 mod1 killing power on tap.

Switch 318 mod 1 or m855a1 into my 11.5 and it's even more terrifying.