Mr. T (MrT4) said:

And do you think Pilots and mechanics, needed an AP round and realy got into the thick of it with the taliban?

Nope.  But they did need a weapon that could do more than just "deter and suppress the enemy for a moment or two and inspire some courage" to themselves before they got killed.

Mr. T (MrT4) said:

Last round of PDWs that went in search of AP performance netted us special low power calibers  5.7x28 and 4.6x30

Yes.  And your point is...?

stancrist said:

Also, it may adversely affect the morale of support troops to have weapons incapable of defeating enemy armor, while infantry does

It's highly unlikely any weapon smaller than the 6.8 NGSW Spear is effective against modern hard armor. 

So the question I'd posit to you is, if thats the case, is there value in issuing any defensive weapon thats not the 6.8 NGSW (or its rough equivalent)? 

If you go back in this thread, tI postulated a pistol size  cartridge that should be able to. The ballistics are very short range compared to 6.8x51. but velocity higher than 1200 m/s

At last something we agree on.

stancrist said:

Mr. T's post is cynical and inaccurate.

I disagree it is spot on. This is what the PDW concept is for.

stancrist said:

Yes, the PDW should be more capable, because sometimes there won't be a machine gun that you can get to.

No there ALLWAYS should be a machine gun that you or your mates can get to. This is not optional. Even with rifles you NEED MGs to win a firefight. The less proficient your riflemen are the more important MGs become.

stancrist said:

When the rear echelon troops of the 507th Maintenance Company were ambushed in March 2003, their sole .50 Browning reportedly did not work.

This is not argument against PDWs and for rifles but against the leadership and maintenance of said unit. Actually to me this short sentence sounds like an investigation for neglect and bad leadership is required. How can this happen? Why is their main assent not in working condition?
I also would question why do they only have one to begin with?

stancrist said:

When Taliban fighters infiltrated Camp Bastion airbase in September 2012, pilots and mechanics armed themselves with rifles to fight the attackers.

Obviously this has not been a situation whre PDWs are required. If you have time to gear up or even go to the armory obviously you don't need to rely on a PDW. Which BTW is the classical approach. Why bother with a small weapon on the person if a big one is just a stoll to the armory away. This approach has been found wanting and the PDW concept emerged.
And just like in the previous case to me it seems the real question is not about weapons but tactics, SOP and leadership. How did the Taliban manage to infiltrate an airbase? This seems the pressing issue that needs to be adressed. Thinking about small arms for pilots is like taking Aspirin against a brain tumor. It does nothing against the cause but numbs the pain. This is the oposit of a solution. Its accepting the status quo but making it a bit more plaletable.

what about a 9mm round that can be interchanged with 9mm luger.  70k PSI and a 9mm sabot

To be quite honest I am beginning to think that the STENG CPW in 5.7 might be the ticket if one doesn't want to go down the high energy route.

https://en.wikipedia.org/wiki/ST_Kinetics_CPW

graylion said:

To be quite honest I am beginning to think that the STENG CPW in 5.7 might be the ticket if one doesn't want to go down the high energy route. https://en.wikipedia.org/wiki/ST_Kinetics_CPW

Or an MP7 in 5,7. The CPW and the MP7 seem to be pretty similar.

schnuersi said:

Or an MP7 in 5,7. The CPW and the MP7 seem to be pretty similar.

weights and dimensions are closer to MP9 than MP7 IMO.

graylion said:

weights and dimensions are closer to MP9 than MP7 IMO.

Seems hard to tell.
The CPW looks remind me of the MP7 prototypes. Its entirely possible that it would have to be beefed up to meet some requirements. Just as it happened with the MP7.
But in general I agree. If is acceptable for service this way the slower weigh and smaller size are preferable.