This Chinese website provides plenty of infos on the FGT-203 :
http://blog.163.com/lhp_sg/blog/static/6906538420082393841144
Below are some highlights roughly translated with Google :
Gun Data :
Bore Diameter : 203.2 mm
Barrel length : 45.5 cal. (9,245.6 mm)
Service pressure (full charge) : 329 MPa
Combat weight : 16.396 kg
Length in firing position : 17.70 meters
Length in towing position : 14.38 meters
Elevation : -5 to + 55 degrees
Traverse : ± 25 degrees
Maximum rate of fire : 3 rounds / min
Sustained rate of fire : 1.5 rounds / min
Maximum road speed : 70 km/h
Maximum cross-country speed : 35 km/h
Projectiles (ERFB-BT / ERFB-BB) :
- mass : 95.6 kg / 100.1 kg
- muzzle velocity : 933 m/s / 933 m/s
- maximum range : ~ 40 km / ~ 50 km
Full Charge mass : 42 kg
Barrel is made of nickel chromium molybdenum steel ESR, using hydraulic autofrettage technology, 64 right-handed rifling. Barrel is chrome-plated to improve service life to approximately 1,000 rounds (ESR ?)
Muzzle brake efficiency said to be 65.9%.
Ammunition Data :
Type : ERFB-BT / Cargo / ERFB-BB
Projectile length (mm) : 1219.0 / 1202.0 / 1239.1
Projectile mass (kg) : 95.9 / 95.9 / 100.1
Maximum range / angle (m @ degrees) : 39159 @ 51° / 36000 @ 50° / 49582 @ 52°
Maximum trajectory altitude (m) : 15135.0 / 13828.4 / 18553.0
Terminal Velocity (m/s) : 446 / 420 / 487
Angle of Fall (degrees) : 63.88 / - / 62.34
Typical PE (range) : 0.44% ~ 0.64% / 0.35% ~ 0.40% / 0.45% ~ 0.65%
Typical PE (deflection) : 0.8 mils
Edit : another useful website (in Japanese) :
http://seesaawiki.jp/w/namacha2/d/W-90%20203mm%BC%AB%C1%F6%DC%D8%C3%C6%CB%A4