Sunday, November 13, 2011
"The auctioneer claims that it is only one of twelve built and the only other known example resides at the Ford Benning sniper school.
The .50 BMG Flechette rifle project was contacted out by DARPA in 1960′s. The projectile consisted of a saboted depleted uranium dart weighing 11.9 gram ( 183.6 grains ).
.50 BMG Flechette round cross section. © Paul Smith (Used with permission)
The sabot was fired out of a smoothbore barrel with the dart achieving 4500 feet/sec velocity. That is more than a 32 grain .204 Ruger!"
Just to be clear, 12 grams is VERY heavy, and 4,500 fps is insanely fast. The energy at impact would be huge, and focused on a tiny point. I doubt this would be effective against modern tank armor, but it certainly will work against even heavy armor on all other vehicles including apcs.
Compare this to a 5 mm/35 SMc - a 39 grain round at 4,250 fps yielding about 1,564 foot-lbs on impact. If we can trust the (absolutely massive) mass above, this round exits the barrel with Just over 8,000 foot-lbs. This is insane considering the tiny nosecone on that dart, but still 4,000 - 6,000 less than a .50 BMG.
By comparison, the Gau - 8 fires a PGU-14/B armor piercing incendiary that is about 425 grams at 3500 fps. This results in 175,000 foot-lbs. That is more than 20 times greater than the DARPA rifle.
The Firearm Blog