Well after tearing thru the brush, they completely tore up a rabbit. The few others were just fired at junk. Plastic bottles, etc. As I said, they tore thru the brush just fine. I never even hinted they were used on a person by me."The rounds I have fired did well in penetrating brush at short range."
What did they penetrate after the brush Rick? Just curious, BTW rock salt penetrated brush fairly well as does 00 and #4 Buck and it will penetrate other stuff as well. The designation for the Flechette round was XM 258 and I have fired several of them, as well as some of the commercial junk. The XM 258 did fly a bit straighter, but it's terminal effects are almost non existent. Certainly NOT the hype you read on line. Here is from Wikipedia
Flechettes
Plastic cases loaded with small steel darts called flechettes were issued on a limited trial basis during the Vietnam war. Cartridges manufactured by Western Cartridge Company contained twenty flechettes 18.5 millimeters (0.73 in) long and weighing 7.3 grains (0.47 g) each. The flechettes were packed in a plastic cup with granulated white polyethylene to maintain alignment with the bore axis, and supported by a metal disk to prevent penetration of the over-powder wad during acceleration down the bore. Cartridges manufactured by Federal Cartridge Company contained 25 flechettes. Tips of the flechettes are exposed in the Federal cartridges, but concealed by a conventional star crimp in Western cartridges. Flechettes had flatter trajectory over longer ranges than spherical buckshot, but combat effectiveness did not justify continued production. Note the weight of the dart!
Here is an excerpt from a D.O.D. publication on small arms munitions effectiveness from 1975. I assume U.S. Navy tests were U.D.T/ SEALS, but that is a guess on my part.
The U.S. Navy first tested XM 258 flechette rounds during the Vietnam War, but found that XM 162 and XM 257 buckshot had far more immediate stopping power. (XM162 is 00 buck and XM 257 is #4 buck, now designated as M 162 and M257)