The same type piece was used by the Germans, French and UK (9.45"). The US reportedly used them as well. Someplace I have a US book on the gun, but I cannot find it at the moment, and I'm not sure if it was on the UK weapon, or a separate US version.
The projectiles are still found on occasion in France and Belgium, the Belgian EOD at Poelkappele have 3 on display, described as one from each country. The only way to tell them apart is by the fuze installed (all are live). In the UK there is a lare collection of theirs awaiting destruction at a certain facility in the SW, there they have several experimental variations as well.
All three countries have tales of there being a CW load, but EOD personnel at each country's CW collection areas people will tell you that while they suspect the possibility of a CW load, no one can confirm it. No CW loaded 240s have been found in decades, if ever. I'll try and look up some photos of recovered HE rounds later.