The future replacements of M16 are here now, and are being used in combat by US forces today.
First... The Heckler Koch XM8 (US gussied over futuristic HK G36) is apprently dead as a project in its old state - the gun had some unresolved tech issues and competing manufactures complained that HK and the Army were working too closely on the project.
So HK are now pushing their new HK416 (5.56) and HK417 (7.62x51) in the US Military/LE market. The HK 416/417 are M16/M4 pattern weapons with a gas piston and other reliability improvements over the M16/M4 - like easier cleaning and use of the durable HK steel M16 30 round magazine. As for G36 HK G36 is no longer even being imported to the US, apparently.
The HK 416 is currently being used in combat by US forces and is employed by LE.
- Some Army units are currently fielding thgis weapon in combat in Iraq.
- I have heard directly from members of one large east coast SWAT team that has dumped their HK G36 (because they lost zero due to heating of the composite parts) in favor of the new HK 416.
See here to learn more about the HK 416:
HK official site:
http://www.hkdefense.us/pages/military-le/rifles-carbines/hk416.htmlHK community site - this includes story and images of combat use of HK416 by US army in Iraq:
http://www.hkpro.com/hk416.htmFurther US SOCOM has officially adopted the FN SCAR in 5.56 and 7.62 NATO to replace it's M4s, and other SOCOM people use the HK 416 as well - both are again in combat alrready.. So there are two modern in use replacements to the M16/M4 right now - though limited in quantity.
Since its based on the familar M16 pattern the HK416 would be a great easy to convert to Assault Rifle for regular US troops who could use a more modern, more reliable and easier to service weapon. Of course we can still debate 5.56, 6.8 and 7.62 ccalibers endlessly after that.