Ian just posted a new video.  The segment at 1:01-1:26 ( https://youtu.be/5Jx9DsbMqew?t=60 ) is interesting because it appears to imply that the Ukraine invasion validates the PDW concept. 

However, in all of the Ukraine vids and pics I've looked at, I have not seen any use of personal defense weapons like the H&K MP7, B&T MP9, or similar.  Has anyone else?

I’ve seen a number of Krinkovs (SBR class PDW) but none of the holsterable PDWs.

I do think the ATGM/RPG strategy does validate either the PDW or ‘light carbine’ concept. 

Namely, if your primary infantry roll is carrying and firing 14-50lb AT/ATGM/HE weapons, then you really want a light and compact firearm mostly for defense or close quarters ambush mopping up.

Something like Ian’s WWSD ultra light AR, as a 4.5lb carbine with 12.5” barrel and 7oz TA33 or Aimpoint T2 would be a compelling ATGM pairing.

gatnerd said:

I do think the ATGM/RPG strategy does validate either the PDW or ‘light carbine’ concept. 

Namely, if your primary infantry roll is carrying and firing 14-50lb AT/ATGM/HE weapons, then you really want a light and compact firearm mostly for defense or close quarters ambush mopping up.

Maybe I'm terribly mistaken, but I think no army considers "carrying and firing 14-50lb AT/ATGM/HE weapons" to be an infantryman's primary role.

Typically, an infantryman will be carrying only one of those 14-50 lb weapons, and once it has been fired, he reverts to his primary role of rifleman.

Which is why those soldiers are usually armed with the standard infantry rifle, not a holsterable PDW or ultra-lightweight, special purpose carbine.

P.S.  Where I did see some validation of the holsterable PDW concept is in the videos of Russian tanks which suffered catastrophic hits. 

Once the tank starts burning, the crew un-asses the vehicle muy pronto.  Any PDW not attached to their body is going to get left behind.

stancrist said:

Maybe I'm terribly mistaken, but I think no army considers "carrying and firing 14-50lb AT/ATGM/HE weapons" to be an infantryman's primary role.

You are propably right. The primary role of a German infantryman is to carry munitions for the squads MG and other heavy weapons... :P

What is an infantrymans main weapon depends on theatre, opposition, doctrine and tactic. IMHO it can be debated if mech infantrymen need rifles.
As can the infantrymans main asset in an environment with plenty of heavy weapons and AFVs.

stancrist said:

P.S. Where I did see some validation of the holsterable PDW concept is in the videos of Russian tanks which suffered catastrophic hits. Once the tank starts burning, the crew un-asses the vehicle muy pronto. Any PDW not attached to their body is going to get left behind.

Fully agree.
As a former tanker I have said this for a long time. AFV crews need a weapon that can stay conveniently attached to their body all the time. Otherwise the weapon will not be available if really needed. This is why I think a rifle or carbine is not suitable. To large to unwieldy. A PDW is the ideal choice.

stancrist said:

Maybe I'm terribly mistaken, but I think no army considers "carrying and firing 14-50lb AT/ATGM/HE weapons" to be an infantryman's primary role. Typically, an infantryman will be carrying only one of those 14-50 lb weapons, and once it has been fired, he reverts to his primary role of rifleman. Which is why those soldiers are usually armed with the standard infantry rifle, not a holsterable PDW or ultra-lightweight, special purpose carbine

I'd say its a new concept we're seeing developed right now by Ukraine; the Infantryman as primarily HE lobber rather then Rifleman or MG ammo bearer. 

But for David v Goliath conflicts (Ukraine/Tiny Baltics v Russia; Taiwan v China; Cyprus v Turkey; etc) I think this format is likely to be more developed. 

Namely, have a dispersed light infantry who cannot be easily spotted and targeted from the air, whose primary weapon is either an ATGM or MANPAD, and whose goal is to quickly inflict losses on an invading force before dispersing to fight another day. 

For those sort of states, I really think this is much more useful then traditional rifle/mg teams in the field trying to pin down forces for artillery and airstrikes 

...

In terms of 'whats the ideal sidearm for an ATGM/MANPAD' I dont think the Holsterable Class (MP7/MP9) is right, because as you mentioned once they fire their single shot they have to revert to rifleman. Holsterable makes more sense to me for a multi shot, reloadable weapon like the AT4 / Milkor.

I think exploring 'light carbine' PDWs may be worthwhile though for this role, with a goal of a 'ready to go' weight of 6lbs. This WWSD is a nice example of the concept, but obviously a more military tested option would be needed.

The sheer numbers of ATGMS and Manpads in Ukraine is not a realistic proposition, here we basically emptied the whole NATO stock to arm a country of 40 million . Tank hunting teams are specialists not every line infantryman is atgm operator. 

Grenadiers (RPG and 40mm) hunting IFVs and resupply missions would be a doable option though. 2 RPGs and/or 40mm, 1 MANPADS for any top cover, 1 SAW/MG, and every one else spare ammo for the above.

I think the ‘ATGM Army’ is actually pretty affordable.

For the cost of a $6 Million MBT, Estonia for example could purchase 150x NLAWs. When we factor in tank training, maintenance and tank ammo, I’d guess 200+ NLAWs. 

It’s even better for a small country that relies heavily on a conscript / militia defense plan, as training to operate a ATGM is so much less then training a competent tank/IFV crew. Ditto a MANPAD vs pilot.

And most importantly, a well dispersed supply of ATGMs is much less vulnerable to air attack then a tank, as they cannot be easily spotted.

That said, I think there would be a need for a more affordable system. Something like the Pzf3 (with its battleship killing 900mm RHA defeat) paired with a lower cost ~$5k FCU. That would allow for a $10k tank killer to help supplement ATGMs.