Vince,I obtained some 2.0mm wide x 0.3mm copper strip from Ages of Sail. I cut it to 9.0mm length and bent it around a 1.5mm drill bit to make the trunnion band for the gun carriages. It came out pretty good, but the photo is a little blurry (crappy camera).
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A bit too late, but... I make my brass strips from plates which are available on eBay. Any thickness between 0.05 mm and 2 mm available - being this our range. Then I cut strips of it on the circular saw, with a 'metal' blade (can also be used for cross-cuts in timber). Cheaper, the exact size what is needed and you don't have to wait for the strip delivery. For convenience I put masking tape on both sides of the plate before cutting.