Where you store them also plays a major part.
Storing the guns in a closet or basement is a good source of rust.
Both are damp and will cause rusting.
Storing in a gun safe without a dehumidifier like a "Golden Rod" device will rust guns.
Storing in a fleece lined gun case is almost certain to cause rust.
There are several methods of limiting or stopping rust on firearms.
1. Apply a coat of a rust proofing lubricant.
CLP Breakfree is one of the very best. Just apply a thin coat and reapply whenever you handle the guns, or periodically. There's also a LP version that's supposed to be even better for storage.
As long as you maintain the thin coat of lube and store the guns in a cool dry place, the metal won't rust.
2. Do what museums do with antique arms and armor.... Apply a coat of wax.
Johnson's Paste wax or even better, Renaissance Hard Carnuba wax is used to prevent rust but not require constant attention.
Renaissance was developed by museums for this specific purpose. It's sold by Brownell's and other sources. A small jar goes a long way.
3. Store the guns wrapped in VCI Vapor paper and the special plastic bags.
The VCI paper gives off a vapor that drives out moisture and air and surrounds the metal with a vapor that totally prevents rust for at least 10 years.
You must use the special plastic storage bags, NOT ordinary plastic bags.
Ordinary plastic passes air and moisture and allows the vapor to escape.
Simply wipe the metal with a thin coat of CLP or LP to neutralize any fingerprints then wrap in several sheets of the VCI paper and seal tightly in the special plastic bags.
The gun will be rust free for at least a decade.
http://www.brownells.com/.aspx/pid=1197/Product/GUNWRAP-trade-PAPER
http://www.brownells.com/.aspx/pid=1154/Product/TRIPLE-TOUGH-trade-PREMIUM-STORAGE-BAGS