50 Caliber LRT
Not very much information available on this one. It was in experimental stage over at
the Olin plant in Alton a few years back, and has evidently been upgraded to limited
production at the Lake City plant. These special ball type projectiles have a mild steel
core that protrudes from the back of the jacket about 1/2". This protrusion is
machined square with 4 small "fins," then drilled for a tracer cavity. In
flight, at normal engagement ranges the round has full velocity 
and lethality. However, at
about 1000 to 1200 yards, the rear protrusion disturbs the air foil to the point that the
round literally drops from the sky. This reduces the chance of casualties from friendly
fire in limited engagement areas both from high elevation firing and ricochets.
Projectiles weigh about 670 grains, and are identified by a light "baby blue"
tip similar to the older M1 Incendiary.
They are known as 50 Caliber LRT, for Limited Range Training. These particular bullets have a tracer cavity, but no tracing compound. They have all been machine pulled from US GI ammunition with the Army's new puller. This latest toy, while an efficient bullet puller, leaves large "traction" marks on 2 sides of the projectile. We have run these bullets all through a set of draw dies to insure the proper diameter and eliminate high spots caused by the puller, but the marks are still noticeable. This is probably only an appearance problem, and probably does not effect the performance of the bullet. We say "probably" because this is such a rare projectile, that so far we have not found any new bullets to have a side by side comparison.
One shooter had some of these filled with tracing compound and fired them into the wild blue yonder to observe the flight. He saw them fly out with normal flight path and velocity. At about 1000 to 1200 yards, they slowed to a stop, hung there for a few seconds, then fell like a rock! These appear to be the answer for areas where overshooting the backstop would be a real concern.
Back to 50 Caliber bullet list.