In my career if 55 years I was a commercial photographer. Through much of my career I stored cameras and lenses in cases with closed cell phone. Halliburton, Pelican and many others use closed cell phone in their cases. Granted guns are valuable but professional cameras and lenses are way more expensive than the average gun. Motion picture lenses can easily exceed $100,000 for a set of lenses and a single Hasselblad digital camera without a lens can run $85,000.

In the 55 years I was in the biz I never say a camera or lens damaged from closed cell foam.

I have a few guns in cases with foam but typically have my handguns in high quality gun rugs. I take them out a couple of times a year and wipe them down with a silicon cloth and run an oiled patch through the chambers and barrels. My king guns are in another safe and not in a case or sock. The humidity in my home runs on average45% and in my king gun safe I have a goldenrod just for safety. Even then I take them out a couple of times a year and wipe them down and run an oily swab through the barrrl. Again I’ve never had a problem.