All, I will be ordering some ballast for the Lackham Museum and Woodland Railway tomorrow (7.25", heavy duty rail). My source is a local quarry who have offered to me on very generous terms. I have been offered some 10mm ballast (that's the true scale size), but it seems a little small. I can get larger if I ask. The bed will be 4" deep 8" wide and lines with a permeable membrane. When the track is laid a further 2" depth will be placed around the sleepers to hold the track in position. So, is 10mm too small? What size have others used on their railway? Regards Peter MODEL ENGINEERING DISCUSSION LIST. To UNSUBSCRIBE from this list, send a blank email to, modeleng-request@xxxxxxxxxxxxx with the word "unsubscribe" in the subject line.