A 50 grain .356" bullet would be awful short.
Nah, I'd have to see that 2,000 fps to believe it.
What he said.
Assuming lead, that would make the bullet 0.175 inches long. Not a very stable bullet design at that diameter.
Which implies that the bullet must be made of less dense material in order to get a geometry that would be stable in flight. Possibly in combination with a pretty impressive hollow point.
Here's one review I found on it, full of blatant BS hype:
Liberty Ammunition’s USM4 UltraDefense® handgun projectile is a monolithic, hollow- point, lead-free handgun projectile that significantly outperforms traditional lead-based handgun ammunition across every metric. Liberty Ammunition’s handgun rounds have historically only been available to the Military because of their lethality, and have up until recently have been guarded by the Department of Defense under a Level III secret review. Now, after customization specifically for US Law Enforcement and Civilian Handgun Markets, the breakthrough performance projectiles are for the first time being made available to a broader target audience.
In recent independently validated live fire exercises conducted for members of the US Military and various foreign defense contractor leadership, Liberty’s USM4 demonstrated heretofore never witnessed performance. USM4’s 9MM, 45ACP, and 40 S&W projectiles achieved more than 2,000 fps velocity, making them the fastest known handgun projectile in the world. USM4’s velocity and unique design characteristics enables the projectile to overcome historical range, accuracy, and stopping power issues typically associated with handgun ammunition. In the performance demonstrations, USM4 achieved less than two inches of dispersion at 25 meters and greater than 12 inches of penetration in ballistic gelatin.
http://www.tactical-life.com/products/liberty-ammunition-usm4-ultra-defense-ammo/
There's a marketing link to USM4.com at the bottom of the article for more information.
Having served 20 years in the military myself, and currently trained in authorized deriviative classification, I don't believe I've ever heard of a DOD "Level III secret review". Perhaps someone else can enlighten me on this.
Personally, I like this exerpt from the USM4.com site:
In ballistic gel, this round has achieves 12 inches of penetration and a permanent wound cavity greater than 5 inches in diameter. This translates in to a faster, more powerful round capable of catastrophic wound damage with 16% less felt recoil.
Never mind that this "DOD" tested round would have the effective range of a hand-tossed rock, with that diameter and mass, and would probably suck penetration-wise through such things as clothing and minor obstacles.
But hey...I suppose the magic 2,000 fps will sell.