Thanks a lot for your feedback Andy and Aart!
And yes, the next guns are from Elswick! Armstrong's 6 inch BL. A well known naval gun, used in several classes of HM ships as main or secondary artillery. Also well known as garrison guns in many Imperial coastal fortifications.
The blueish gray is after the color found in a delightful late victorian plate. I really don't know if the wall of the barbette mount is of brick, earth or concrete, so it can be historically inacurate. The Vavasseur garrison mount is very similar to the mounts of this type found in RN vessels. Finally, I made my best in the shading of the gun parts which are behind the shield, but I don't know if it is according SB standarts (so I'm completelly open to corrections). Cheers.
PS1: It is very hard to find french guns!, especially the heavy ones, in fact the only clear ones that I found was the 240 mm Mle 1884... and the first Paixhans!!!.