Copyright International Ammunition Association, 2009. All rights reserved.
Cartridge of the Month November 2009

5.56 x 45 Experimental AP by Fabrique Nationale
Specimens and photos courtesy of Paul Smith

With the development of this caliber came the need for a variety of loads, including armor piercing. Among the early attempts was this load by FN.


The projectile consists of a solid brass projectile into which a hole has been drilled into the base and a hardened steel penetrator inserted. These rounds are identified by the brass bullet material and a black tip (although the tip color is often worn off). Hughes states that the penetrators are of tungsten, but of the several rounds that I’ve sectioned, all have been steel.


The other very interesting ‘discovery’ revealed by sectioning is a longer bullet variation. The construction is identical in that a brass projectile and steel core inserted from the rear.


Both rounds are headstamped F N 66 and have black bullet tips. The only way to distinguish the loadings is by weight or x-ray. Unfortunately I did not weigh the ‘unknown’ variant prior to sectioning as I simply did not notice and was not expecting this variation.


Reference: The History and Development of the M16 Rifle and Its Cartridge. David Hughes, 1990. pp. 111-112.

Copyright 2009 by the International Ammunition Association, Inc. All rights reserved.

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  Revised 9 November 2009