I have one of the tillia units that uses rolls of bags. I've put complet rifles in them and just let them lay in the corner of the basement. My HK91 lasted about 1-1/2 years before a couple of pinholes started leaking air.

I wrap anything with sharp corners in old socks. I heat the socks up to just about 200* hoping that will remove any mosture. I can fit s1 or 2 magazines into a sock.

I put away a pair of BDU's about 10 years ago with some pine needles in the bag. I just opened the pants 2 weeks ago. They seem none the worse for the length of time. They did shrink a couple of sizes though :p

Sharp edges and rough handling seem to be the major problems with rigid items. Clothes are just a no brainer.