At the risk of boring everyone, I would refer y'all to my note of the 17th, in which I stated that no one in the Ironclad museum in Rotterdam in the Netherlands could show me any conclusive evidence that any form of protective screening was ever used in the lining of the casemate in this vessel currently on display in Holland or any other of the period (1868).
I further checked Hammersleys book on Ironclad design dated 1879, and in the chapter on typical Turret and Gun installations, despite the presence of several drawings of various casemate/turret interiors- there are no signs of any protective netting, or wicker work or whatever.
Certainly in the case of wooden ships which utilized boarding nets, some protection was provided to the gun crews, in that falling blocks and shattered spars often wound up in this netting, along with any boarders that might have made it that far. But down on a gun deck, the last thing anyone wanted was the possibility of overhead netting drooping down and catching on a recoiling gun and carriage, also gun decks are often dark and pretty cramped without much headroom, imagine trying to work round the netting with a long handled barrel cleaner and scraper, I dont think netting would be found on board after the first gun action!!
And finally, I am afraid you are all looking at this from a 21st century standpoint, crew safety was never seriously considered until the turn of the century, flash curtains came into general use following the loss of several ships in the 1914-18 war, and that wasnt for the protection of the crew as much as it was to prevent the loss of the ship.