Christian at Defense Tech broke a story on Congress and the M-16. This past weekend, some Congress staffers went to Quantico to get an orientation on "commercial" alternatives to the Colt M-4. There has been no updates on what happened this weekend, nor which vendors/weapons showed up at the orientation. It probably included the HK416, HK XM-8, and the FN SCAR-L, which were in the recent Army rifle endurance test. Rumors state that the various 6.8 SPC, 6.5, et al, cartridges and platforms would have been present as well.
It's nice that the Congress people got to play w/ guns. I hope that they included some real American vendors such as LWRC, POF-USA, and Ares, who have already brought piston-operated ARs to the market successfully.
Other than the HK brand name and some quality control advantages, HK does not have an edge in this arena. LWRC and Ares both use the tapped rod, AR-18 mechanism on the HK416 and XM-8. The whole point of a piston-operated system is to be resistant to fouling. If you tighten the tolerance, like what HK likes to do, you lose the robustness advantage. It's interesting how the "greatest gun company", as HK fans likes to tell you, does not get that idea. Tightening the tolerance will give you accuracy, but also increases maintenance requirements, as we have seen w/ the MP-5/G-3 system.
Later I'll talk about what this M-4 controversy says about the modern military small arm philosophy.
UPDATE: Participants reported that Barrett, FN, LWRC, HK, and Bushmaster provided equipment to the demonstration. The demonstration was reportedly very professional, with no commercial sales pitches and stuck to the numbers and facts. The calibers were 5.56, 6.8 SPC, and 7.62x51mm. It's great that LWRC participated in this demonstration.
Personally, I'm agnostic on the 5.56 vs 6.8 vs 7.62 debate. Line units may benefit from switching to a heavier caliber. However, the low recoil of the 5.56 enabled better marksmanship among rear echelon personnel and soldiers of smaller stature.
Dr Roberts (CDR, USNR) has made a persuasive case for upgrading to 6.8, tho.
One last point: It is important for the layperson to realize that switching calibers or to piston operated gas systems does not require us to abandon the M-16 platform. The M-16/M-4 has two sub-systems, the Upper Assembly and the Lower Assembly. The lower assembly contains the trigger and the stock, and generally stays the same among most M-16 variants. The upper assembly has the barrel and is the main difference among the various calibers and operating systems. If we were to upgrade the M-16/M-4, we can just buy new upper assemblies or modify our existing inventory of upper assemblies.