|Ever since the US Military and other NATO members decided to replace the 7.62x51mm NATO
(.308 Winchester) with the smaller 5.56x45mm NATO (.223 Remintgton) as the work horse for
the NATO countries infantry, manufacturers have been coming out with new calibers to improve
performance and terminal energy without increasing recoil and reducing accuracy.
Now with the popularity of the AR-15 (the semi-auto, civilian brother of the U.S. military's
(M-4) many new calibers are becoming available for the (easy to change) upper units of the
AR-15 and M-4 for hunting and military uses.
In recent years 6.5 Grendel, 6.8 REM SPC, 50 Beowulf, .499 LWR, alongwith the Russian
7.62x39 are just a few calibers now available.