Length, dimensions, and possibly caliber. The 600 was made in calibers the 400 was not.
Not exactly a drop in proposition. You need the services of a gunsmith.
100-400 USD or so
The difference is 360. Find it out by doing 400-40=360
8755 - 8355 = 400 8355 - 8755 = -400
size of the motor
100-400 or so
400 has a longer stroke
The difference between them is 3,600 meters.4 km is ten times as long as 400 m.
1700 feet
-200
0.4 litre = 400 milliliters
The difference between 100 metres and 400 metres is 300 metres.