For what it's worth...
There are a number of ways to secure your guns. Several are mentioned in prior posts. IMHO, however, there is no substitute for a sturdy gun safe, for both security of your guns and peace of mind when you're not at home. (As an aside, many states, even the semi-Socialist state of Connecticut, holds you harmless if your gun was acquired by a criminal act, ie., burglary, whether or not it was locked at the time. Check your local laws but if you don't want them stolen, you've got to lock them up).
You can use any number of clever home-made means to secure your guns, but I still suggest a safe. For the heirlooms, a fireproof safe. There are lots of options. I have a small fireproof lockbox, big enough for half dozen pistols, that cost only about $ 40. Probably you would compromise the fireproof integrity, but it could be drilled and bolted to the floor from the inside. On the other hand, i only use it for birth certificates, passports and other papers.
For my guns, i went with a Sentry safe. Combination dial, three 1.5" solid hardened steel bolts, entire cabinet made of rigid, welded plate steel (avoid the cheap filing cabinets some companies sell). It's heavy (about 250 lbs - my son and i both nearly killed ourselves toting it upstairs to my office) but not fireproof. It is predrilled, and bolted very solidly to both the floor and to BOTH sides of the corner in which it sits. (hint - because of cove moldings, i utilized an appropriately drilled wooden shim on each lag bolt, between the safe and the walls to keep from pulling it askew when i tightened the bolts). It safely and securely holds 6 rifles, two shotguns, three handguns, and approximately 2000 rounds of various calibers and gauges. I've also seen an aftermarket hangar that attaches to the inside of the door and comes with a number of velcro-attached holsters, adding enough space for up to 8 more handguns. Try CheaperthanDirt.com or Sportsmansguide.com.
The best part? I got the safe in the winter, after hunting season, at Walmart for the clearance price of less than $ 180. Look around for a deal. If you have to, use a credit card and pay it off over time. But if you insure your car, and your house, and your life, why not a little extra insurance for your prized possessions?