stancrist said:

The main advantage of an SBR for the medic (and certain other individuals) is commonality of ammunition and magazines with the riflemen in the unit.

That only applies if the medic is assigned to an infantry unit.
It also is not really relevant since a medic is not armed to actively participate in a firefight.

roguetechie said:

Realistically that's a pretty steep price and performance delta.

The price for a private purchased gun and ammo is no benchmark for governmental procurement.

roguetechie said:

Will it be less convenient? Sure but I can live with this.

The fun part is with such short barrels military issue 5,56 looses so much performance its in PDW territory. The same can be achieved with a smaller and lighter cartidge and a smaler gun.
The 7,5 FK delivers comparable performance from a 6" barrel. The 95 grains bullet retains ~700 J at 100 m. With a 10" barrel the performance certainly would be even better. At the same time the cartidge is shorter than a 5,56x45 and can be used in magazine in grip configurations. A MP7 or MP9 like weapon in this caliber makes SBRs and carbines redundant and it makes an effective handgun round should this be desired.
IMHO its the best current solution to this problem.
Its not easily and cheaply available for personal use though. I hope this will get better in the future.

schnuersi said:

       stancrist said: The main advantage of an SBR for the medic (and certain other individuals) is commonality of ammunition and magazines with the riflemen in the unit.

That only applies if the medic is assigned to an infantry unit. It also is not really relevant since a medic is not armed to actively participate in a firefight.

Actually, what is not really relevant is if the medic is not armed to actively participate in a fight.

Also, the advantage of mag/ammo commonality applies not solely to medics, as I noted above.

For example:

Talking about the 7.5 FK. That is a lot of cartridge and needs a bigger gun. Not sure that that is the way ...

I agree.  The 7.5x27 FK is a much fatter cartridge than 4.6x30 HK and 5.7x28 FN, which would substantially reduce magazine capacity relative to the smaller rounds.

Also, the 7.5 FK is considerably heavier, with bullets which weigh three times as much.  I don't see a logical reason for advocating 7.5 FK as a military PDW cartridge.

stancrist said:

which would substantially reduce magazine capacity relative to the smaller rounds.

The handguns in 7,5 FK have a magazine capacity of 15 rounds. Which is what a typical 9x19 service pistol has. So it can be safely assumed the capacity of a larger magazin is also comparable. Which would mean a 30 rds magazine is of reasonable size.

stancrist said:

Also, the 7.5 FK is considerably heavier, with bullets which weigh three times as much. I don't see a logical reason for advocating 7.5 FK as a military PDW cartridge.

IMHO the 7,5 FK adresses the criticism or potential shortcomings of the 5,7 and 4,6 PDW cartidges. Lack of power and low mass projectiles. The 7,5 FK indeed is more powerfull. Which means its in the performance range of 5,56x45 from SBRs. This also offers potential for improveing in armor piercing performance. While the large and heavy ball type bullet has significant stopping power.
Yes the cartidge is heavier than the the smaller two. But there is a price to pay. Its either performance or weight.
I have no idea how the 7,5 FK would perform in a full auto weapon. I guess its less controllable than 4,6 or 5,7. More like 9x19.

schnuersi said:

The handguns in 7,5 FK have a magazine capacity of 15 rounds. Which is what a typical 9x19 service pistol has. So it can be safely assumed the capacity of a larger magazin is also comparable. Which would mean a 30 rds magazine is of reasonable size.

Yes, like I said, magazine capacity of 7.5 FK would be reduced relative to the smaller cartridges:  15 rds vs 20 rds for a flush mag; 30 rds vs 40 rds for extended mag.

schnuersi said:

IMHO the 7,5 FK adresses the criticism or potential shortcomings of the 5,7 and 4,6 PDW cartidges. Lack of power and low mass projectiles. 

This also offers potential for improveing in armor piercing performance. While the large and heavy ball type bullet has significant stopping power.

I have no idea how the 7,5 FK would perform in a full auto weapon. I guess its less controllable than 4,6 or 5,7. More like 9x19.

Considering velocity and bullet weight, full-auto controllability should be more like .30 Carbine.

And .30 Carbine Ball does not have a particularly spectacular reputation for stopping power.

My main concern is actually size and thus carryability of the gun.

I have no reason to think that a 7.5 FK PDW would be any bigger than the MP7.

stancrist said:

Considering velocity and bullet weight, full-auto controllability should be more like .30 Carbine.

Controllability also depends on the weapon and its layout not only the impulse of the round.
It would have to be tested how controllable a modern gun is when firing such ammo in full auto.

stancrist said:

And .30 Carbine Ball does not have a particularly spectacular reputation for stopping power.

No but the .30 carbine ball is a legacy design round nose bullet. The 7,5 FK has been designed with stopping power in mind. It is advertised as having better effect/stopping power than .357 mag.
How a military loading would look and work is unclear. I think the standard load for the 7,5 FK is not Hague/IHL compliant.
Same with an AP bullet. Depending on design it could be really good or not so much.

Never the less the 7,5 FK shows that SBR like performance from an handgun or PDW sized weapon is possible.