I came to that realization myself.
After several seconds of consideration.
Just for a moment thought the article was about Combustion Light Gas Guns scaled down to hand held size. The CLGG is the forerunner technology before the Navy switched track to pursue the electric rail-gun.
The technology demonstrator started with a 16mm round, went to 45mm, and finally 155mm. 4km second or about 13,000fps velocities were achieved. Inconsistent ignition of the propellant charge, thus inconsistent chamber pressure presented as a problem for the 155mm scale prototype. Hitting a target at 200 mile range with a dumb round wasn’t possible with this condition.
http://www.dtic.mil/dtic/tr/fulltext/u2/a462130.pdf
https://www.aa.washington.edu/files/research/ramaccel/publications/STA-witherspoonOct2000.pdf