Interesting post. The fact is the current 5.56 (SS109/M855) IS A EUROPEAN DESIGNED CARTRIDGE!
In the mid to late 1970s, NATO was deeply involved in the “Weapon System of the 80s” trials. At that time the US 5.56mm cartridge was the M193 which was not perfect but at the time was seen as having pretty good terminal effects. It was exclusively used in the various versions of the M-16.
Because of the politics associated with the selection of the US designed 7.62x51mm over the British 280/30 (the British wrote an excellent history of the entire process which I had a chance to read 35 or so years ago - wish I still had a copy of it). The US eventually decided not to submit anything to the trials. The SS109 with the 62gr bullet instead of the 55gr bullet of the M193 was the Belgian submission and won the trials. I believe the heavier bullet was intended to make the projectile more stable and more suitable for a Squad Automatic Weapon in 5.56 for use in place of the M60 and similar NATO SAW weapons in 7.62 NATO.
Both the British and Germans had submissions. I know that the US was looking at a shortened version of the 5.56x45mm cartridge during this time frame but decided not to submit it (or so I’m told). I seem to remember that there may have been other things considered by the US. I have also heard rumbles at the time from the US Army that they were not entirely pleased with the redesign of the M193 into the 5.56mm NATO.
In this time frame I was serving with the British Forces and had an opportunity to visit the NATO test center at Cold Meece (near ROF Swynnerton) and spent the day with the Major commanding and we had extensive discussions about the trials since Cold Meece was deeply involved and the Major had strong feelings on the subject. I also visited the British Ordnance Board during this time and had a couple of opportunities to discuss the trials with the head of the Ordnance Board (a Royal Navy Captain for the first time) and some of his staff. The above is from my memory so may be off in some details.
Over the past 5+ years I have heard some opinions in the US military circle (mostly from old guys like me) that some of the “stopping power” problems in Afganistan and Iraq are the result of trying to do too many things with the 5.56 NATO which led to the M855, and that the M193 had considerably more stopping power. This may just be old guys talking (although some very knowledgable old guys). Clearly the longer ranges, particularly in Afganistan has something to do with it.
The bullet tip design of the Soviet 5.45mm seems to give it considerable stopping power from what I have heard.
Retaining the 7.62x51 as a rifle cartridge is not the answer. I carried an AR-15 in Vietnam in 1966. I also had lots of opportunity to fire an M-14. On fully automatic, the M-14 was essentially useless compared to the AR-15 based on my experience. Weight was and still is a big issue. I have always thougth the M-16 in 5.56mm paired with a SAW like the M-60 in 7.62 was a pretty good combination, but then I was never an infantry guy but many of my peers seem to have considered them a pretty good combination-once the initial M-16 problems were solved.
Still, it is amusing that we are talking about a European designed NATO cartridge this time since that is what we have had for 30 years.