PMC 556X is a 5.56×45mm NATO rifle load from PMC’s X-TAC line, built around a 55-grain full metal jacket boat-tail (FMJ-BT) projectile for reliable feeding, consistent external ballistics, and high-volume training use in 5.56 NATO–chambered rifles.
 
Key Features
55-grain FMJ-BT projectile – Full metal jacket construction supports consistent feeding and limits deformation, while the boat-tail profile helps maintain stable flight.
5.56×45mm NATO pressure/format – Intended for firearms chambered in 5.56 NATO, with typical M193-style ballistics.
Training and general-purpose focus – Designed for range work, drills, and function testing where repeatable performance matters.
Brass-cased, boxer-primed construction – Supports reliable extraction and is commonly suitable for reloading where legal and appropriate.
Non-corrosive components – Uses modern, non-corrosive priming consistent with routine maintenance practices.
 
Specifications
Model number – 556X
Cartridge – 5.56×45mm NATO.
Bullet weight – 55 grain.
Bullet type – FMJ-BT (Full Metal Jacket, Boat Tail).
Listed muzzle velocity – 3,120 fps (16-inch barrel reference; results vary by firearm and barrel length).
Listed muzzle energy – 1,189 ft-lbs (16-inch barrel reference; results vary by firearm and barrel length).
Ballistic coefficient – 0.243 (G1).
Primer – Boxer, non-corrosive.
Case – Brass.
Rounds per box – 20 cartridges.
 
Competing Items
Federal American Eagle 5.56 M193 55 gr FMJ – Comparable M193-style 55-grain FMJ training load.
Winchester 5.56 M193 55 gr FMJ – Similar 55-grain FMJ offering intended for range and general use.
IMI 5.56 M193 55 gr FMJ – Another widely used M193-pattern 5.56 NATO option for training and stock use.
 
PMC 556X is a straightforward 55-grain FMJ-BT 5.56 NATO load aimed at dependable cycling and consistent downrange behavior for training and general shooting. Its brass-cased, boxer-primed format makes it a common choice for shooters who want a standard-pressure 5.56 option in typical 20-round packaging.