Ok, point taken

Thanks for the information, the author of the article really did a great job of summarising all the issues around M855A1, despite the quaint way that the critically important velocity and chamber pressure figures had been left out of publically released official statements. When I wrote the previous question I should have explicitly referred to M995. 

My final question to the forum contributors, before I quit from derailing the discussion in this thread, is what is the current cost per round for 5.56 M995, compared to roughly $14.30 for 7.62 ADVAP and $12.37 for 6.8 SP. And I know I am being slighly unfair due to differring phases of product maturity.

PRM2 said:

My final question to the forum contributors, before I quit from derailing the discussion in this thread, is what is the current cost per round for 5.56 M995

I recall reading it was like $2-3, but thats from long memory. This was at a time when 5.56 M855 was $0.25ish or even less. 

The problem is we've seen from testing done by Buffman is the M995 even from a 22" barrel was unreliable / unable to defeat Level IV from 40' away. 7.62 M993 @ 2850fps from 40' away was also stopped by some plates. 

...

Ultimately NGSW comes down to whether armor piercing capability matters / is a primary factor in cartridge design.

If AP is key consideration, then either a magnum cartridge like 6.8 or a saboted APDS is the correct choice. 

If not then a lighter caliber makes a lot more sense.

Thank you, I suspect most people on the forum are probably of the opinion that 5.56 is good enough for most uses, except AP, and you can work around that with a Designated Marksman and/or calling in fire support.

PRM2 said:

Thank you, I suspect most people on the forum are probably of the opinion that 5.56 is good enough for most uses, except AP,

Arf, that was a point heavily debated "back in the days"...

gatnerd said:

I recall reading it was like $2-3, but thats from long memory. This was at a time when 5.56 M855 was $0.25ish or even less.

Yes, that's right.

gatnerd said:

The problem is we've seen from testing done by Buffman is the M995 even from a 22" barrel was unreliable / unable to defeat Level IV from 40' away. 7.62 M993 @ 2850fps from 40' away was also stopped by some plates.

The "ADVAP / 6.8 mm SP" generation of AP ammo seems to deliver pretty extreme capability, just like the "Stiletto" rounds developped in the UK by Ukrainian designers (that worked previously on the Russian 7N27 and 7N39 rounds if I don't mix the names).

The M993 was capable of defeating 18 mm of RHA at 100 m.

The DM151 is capable of defeating 16 mm of RHA at 200 m, from a shorter barrel.

The "6.5 mm SP" for the Hybrid case Creedmoor could defeat 20 mm of RHA at 300+ m, so better performance than a .50 BMG AP round.

Perhaps we are in a static period of small increments until something world changing comes along. For me, the sighting system is the most technically interesting aspect of NGSW, rather than the high pressure cartridge which has its own set of pros and cons.

There is the intriguing prospect of further developments in neckless cartridges though !!!! But that is in another discussion thread.

PRM2 said:

Perhaps we are in a static period of small increments until something world changing comes along. For me, the sighting system is the most technically interesting aspect of NGSW, rather than the high pressure cartridge which has its own set of pros and cons. There is the intriguing prospect of further developments in neckless cartridges though !!!! But that is in another discussion thread.

Still hoping for telescopic to come off age

PRM2 said:

rather than the high pressure cartridge which has its own set of pros and cons.

Increasing the pressure to 75-80 kpsi is giving you a boost of performance similar to the one achieved during the end of the 1800's with the transition from black powder to smokeless powder.

That's significant enough to reward some attention.

Do you think this is where the future of small arms development may actually go, with 6.8x51 giving confidence that it is a practical concept?