Gerard Demaison is mistaking the 155 C mle 1917 howitzer with the 155 L mle 1917 gun, both manufactured by Schneider.  The range figure is correct for the latter.

When did Romania take delivery of their "matériel de 155 mle. 1917 Schneider long" (L17S)? Was it a prewar acquisition or did Romania receive stocks of them from the Germans after the Fall of France?

155mm schneider howitzer mle 1917 ( France and US )
The range in your posting needs to be revised down. It is listed in Ian Hoggs' " Allied Artillery of WW1 ", and in the US Army manuals of WW1 as 11.5 kms or 12.54 yards. Otherwise congratulations for an excellent site. Best regards.