M855 was a compromise from the start

by Miles Fortis , CIVITATES AMERICAE, Sunday, November 10, 2013, 11:29 (4036 days ago) @ cubrock

It's pretty decent general purpose ammo, but there is much better available. That being said, don't go throwing it away.

When developed, it's primary design feature was the ability to get through then current soviet body armor, even if what got though was nothing more than a ~20 gr piece of tungsten.

A wound, any body entry wound was preferable to merely peppering someone with fragments as a standard lead core bullet disintegrated on hard armor.

The design was state of the art 37 years ago, but technology has advanced.
It's not a bad bullet, but had known terminal ballistic limitations on 'soft' targets almost from the start. Fragmentation is dependent on the yaw of the bullet as it enters the target. And yaw is subject to variables that could never be accurately predicted. So, terminal performance is unpredictable.

It can as easily zip right through a target causing a need for multiple rounds into hajji or tumble and fragment into itty-bitty pieces and he's down for the count.

M855A1 replaced M855 three years ago. It is a completely different bullet design and took almost 10 years to get right.

The lead slug is replaced by a copper slug placed behind the penetrator and the jacket is reverse-drawn instead of forward-drawn around the slug and penetrator. The jacket is swaged into the penetrator which extends beyond the jacket and becomes the point of the bullet.

Hard target penetration is increased. Ballistic gel tests (soft target) show vastly improved performance which was confirmed by combat use in Afghanistan. All ballistic performance, interior, exterior and terminal have been shown to be highly predicable by this combat use and we'll probably not see another change for standard issue until someone finally comes out with that phased plasma rifle.