These Adams Arms Carbine Bases handle similarly, but the 5.45mm version (right) uses less expensive ammo than the 5.56mm (left).
It can be expensive to spend a pleasant day at the range punching holes in paper. The problem can be worse for law enforcement personnel who must maintain their firearms proficiency in order to protect lives. This is especially true for officers who carry an AR-15 if their agency does not supply all their ammo. Even .223 training ammunition isn’t cheap. Some have suggested practicing with an AR chambered for .22 LR using either a conversion kit or a dedicated upper, but the .22 does not duplicate the recoil of a .223. Fortunately, Adams Arms makes AR-15 uppers chambered for a cartridge that is almost identical to the .223 and costs a lot less.
The 5.45x39mm Russian cartridge was developed by the Soviet Union to be somewhat comparable to the 5.56x45mm NATO round, the military version of the .223 Remington. Although the 5.45mm projectile is longer than the 5.56mm bullet, the overall cartridge length of both rounds is about the same because the 5.45mm case is only 39 millimeters long compared to 45 millimeters for the 5.56mm. Common training bullet weights are around 60 grains for the Russian, compared to 55 to 62 grains for the NATO round, and since velocities for both run from about 2,700 to 3,000 feet per second (fps), recoil is similar. The Russian cartridge is readily available because it is used in the AK-74, and military surplus and commercial loads can be found at prices much lower than 5.56mm ammo. So, it made sense for Adams Arms to produce an upper chambered for the round.
These Adams Arms Carbine Bases handle similarly, but the 5.45mm version (right) uses less expensive…
by Dave Bahde / Oct 1, 2012