Readers of this blog know that I am as much of a gun safe aficionado as a gun aficionado.

Over father’s day weekend, my father’s day present to myself was a new gun safe.

I found on Craigslist a used Cannon 24 gun safe for $300.  Usual MSRP is $850.

I immediately bought it, brought it home, and with some help and a heavy duty hand truck from Costco, got it into my master bedroom closet.  It only weights, according to the factory spec, 485 lbs.

Now, if I can get it in that way, other men can get it out that way, so I had to secure it to the floor.

In terms of load bearing, it was in perfect position directly over an engineered trust floor joist.  In terms of security, it was in a bad position as the holes in the bottom to mount the safe were sitting above hardwood and OSB subfloor.

The safe came with four 1-1/2×3/8 in lag screws.  I drilled pilot holes and screwed them into the floor.

I didn’t feel confident about that and looked up the pullout strength for lag bolts.  That information is available, especially if you work for a company that does forensic engineering.

A little math later and a 3/8 in lag screw has about 300 lbs pullout strength in 23/32 in OSB.

That’s not enough.

I didn’t want to cut the trim so the safe has about 1/2 in gap between the back and side and the drywall in the corner of the closet. Enough for some burly guys to get their fingers or a strap behind it and pull it forward.

With the leverage of 59 inches of safe body, that would be enough to pull the lag screws out of the OSB.

I wasn’t going to worry about the front screws, since tipping the safe backwards against the wall would accomplish nothing.  I just needed to increase the pullout strength on the back screws.

I drilled two 3/8 in holes through the hardwood and OSB.  I shoved dowels through the holes to locate them in them in the basement.

Once I did, I hammered 2-1/2×3/8 in lag bolts through the holes, set a 1/2×2 in fender washer, then a 1-1/2×3/8 in fender washer, then a 3/8 in nut with red Loctite, and torqued it down with an impact driver while my beautiful wife held the bolt head with a ratchet in the safe upstairs.

The 2 in fender washer was against the OSB, so to pull it out, someone would have to apply enough force to pull a 2 in steel disk through the subfloor.  I calculated that at about two tons.  It might actually rip the bold head and washer through the bottom of the safe first.

I then tucked the insulation back and replaced the drop ceiling panels in the basement camouflaged the nuts.

Yes, nuts are vulnerable from attack from underneath, but a thief would have to know that’s how I anchored the safe, and know where in the basement to look, and pull down the drop ceiling and insulation to expose the bolts and get a ladder to attack them.

I doubt a thief will go through that much trouble for a closet gun safe when there are TVs to steal.  And any thief with the tools to attack the bolts would probably just attack the safe in place.  While the alarm went off and the dogs went nuts.

I don’t keep much in that safe anyway.  Most of my stuff is in my two Fort Knox safes in the basement.  Those are almost a ton each, with 1/4 in bodies, double lined, and are anchored to the slab with 5/8 in Red Head expanding anchors.  Those you could hook a truck to and couldn’t pull them out.

The upstairs safe holds a home defense shotgun, two of my most used CCW pistols, some cash, and jewelry.  Just things that I wanted secured but was tired of having to go into the basement to get every time I needed them.

I tried to maintain a reasonable balance between cost of security (a light duty safe anchored to the OSB) and what I stored in it.

Since proper mounting of a safe is as important as the safe itself, I thought I’d share with you my engineering solution for upstairs above OSB if you can’t place the mounting holes over a joist.


Yes, anyone could rip open a safe with an angle grinder or metal blade on a Sawzall.

Every time I post about safes someone comes along and tells me how they would go all Ocean’s 11 and steal my shit with the tools they have in their garage.

I don’t care and I’m tired of those comments.  Feel free to keep them to yourself.

I keep saying, and clearly some people are not listening, that the vast, vast majority of home burglaries are junkies and/or teenagers looking for stuff to steal that is easily sold for cash, e.g., electronics, guns, jewelry, etc.

They want in and out fast and they don’t want to fuck around while they are in your house.

They will tug on a safe a few times.  If they can’t budge it they will leave it alone and rip your TV off the wall.

My safes are not impenetrable.  No safe is.  The highest rated safes are TL60, which means engineers from UL couldn’t break in within an hour.

I wanted to express a cost effective way of increasing the security of a low cost safe with better mounting hardware.

So if you don’t understand the situation and you don’t understand the threat, your fantasy of cracking open my safe with a carbide tip tool is unwarranted.

What 99.99% of you, you suburban gun owners in middle-class neighborhoods, need to be worried about is two junkies in your house for 10 minutes max, trying to get as much value out if your home as they can.  A simple safe or job box, anchored firmly enough to keep them from putting it on a hand truck, will make them leave your safe alone and take your TVs, computers, and the other shit lying around. They’d rather spend those 10 min filling their car with your electronics than wasting them trying to crack a safe and driving off with nothing.

That and keeping your kids from touching your guns.

Be reasonable, not a dick.

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By J. Kb

13 thoughts on “Securing a gun safe”
  1. Nice.
    I was thinking along similar lines, except with a hunk of heavy angle iron instead of the fender washers. Also, to avoid the issue of nuts being unscrewed, I’d insert the bolt from below and have the nut inside the safe.

    1. Ideally, a torque washer and carriage bolt would be the best, then you’d just have a smooth head underneath, but that would have been a bear to install.

  2. Anything that spreads the load will work. There is no need for angle iron as that doesn’t increase the surface area. Simple flat bar will work. I’ve got a shop. If I wanted to do over kill, I would put a flat bar in place, drill and tap one end. Then I would mark where the other hole goes by marking it through the hole in the safe. Drill and tap that.

    Now the bolt heads are in the safe and the bar below. There is now way to unscrew the bar from the bottom without unscrewing it.

    ALL of this is overkill. J.Kb has done the math. All it takes is fender washer and bolts that wont strip or break.

    J.Kb. and I had discussions on this a while ago when he pointed out that a job box makes a good secured location to store firearms. It can be attached to the floor and made safe.

    It can always be made more secure. You just got a new safe? Why don’t you wield another 1/2 of steel plate on all sides. That will make is stronger! Well, only sort of. It is all a balancing act.

    There are way to many stories out there of people with high security doors and low security installation. Why worry about how strong the door is when the jamb or frame will fail easily?

    1. I’ve cut more than a little metal over the last few years. It takes time to cut metal. I used a Sawzall to cut 5/8 in thick steel plate, mild steel (A-36). It took over 30 minutes to make two 6 inch cuts. I’ve also cut a 6 inch round in less than 5 minutes on my bandsaw. That was 4140.

      One of the safety items in high security “things” is a free floating cylinder when the saw gets to that free floating cylinder it just rotates so it doesn’t cut.

      Regardless, this is exactly the same argument I lost with J.Kb. the last time he talked about security.

      Something is better than nothing. This is way better than something. There is always a way to defeat something.

      Reference _Butch Cassidy and the Sundance Kid_, to much dynamite.

  3. Important points about the leverage and weight of the safe itself being used against it.

    I honestly never thought about looking for a used safe like that, gives me something to think about thank you. Do you have any idea why they were selling?

    Most of home gun thefts I saw were smashed gun cabinets from hoodlums or the friends of the home owners kids. What wasn’t a glass fronted cabinet were often guns left leaning against the safe that was full. In, out, and away in the night as fast as they can scamper.

    1. It was an estate sale. The husband passed and the wife didn’t want to keep the guns. She sold them to a dealer and I bought the safe.

  4. No safe is perfect. If someone wants in badly enough, and has the time and gear, they will get in, period.

    To borrow a roleplaying game turn of phrase, the trick is to crank the difficulty class of the check so high that it stymies anyone short of Arsene Lupin or the Gray Mouser.

    I like JkB’s style. Making notes now 🙂

  5. RE: your update: If I was really trying to make my guns as unstealable as possible, I’d get the biggest, heaviest safe I could find, bolt it to a two-foot-thick concrete slab in a deep hole in the middle of nowhere, put my guns in, close and lock it, burn the combination and melt the keys.

    Then I’d pour two tons of concrete over the top of it, let it set, cover it with fill dirt and compost, plant trees over the top, and guard the site 24/7 until the trees rooted and grew up.

    I can almost guaran-damn-tee nobody is stealing those guns. Even if you knew which random tree-covered mound to dig up, the expense and effort just wouldn’t be worth it, not even to prove the point that it’s still not 100% secure.

    However, there’s not much chance in me getting any enjoyment from them, either.

    It’s a similar principle as we see in information security: it’s a spectrum. On one end you have accessibility, and on the other you have security. The more secure a system, the less accessible and usable, and vice versa.

    (The grand irony of those “Ocean’s 11” style vaults, is that all that high-tech gear — the palm and fingerprint scanners, retina scans, voice identification, constantly-rotating passwords, etc. — that we think of as “security”, is actually there for accessibility. A hypothetical perfectly-secure system wouldn’t have any of that stuff, because it just wouldn’t be accessible at all!)

    So we make compromises on security to maintain accessibility and usability. True, it’s not 100% safe, because given enough time and attack resources, no system is. But it is reasonably safe — relative to the value of the “goods” — and it’s available to authorized users with (hopefully) just a little hassle. The idea is that unauthorized users will (hopefully) decide it’s a little too much hassle to be worth the risk and effort.

    It’s up to each individual to decide where on that security-accessibility spectrum is best for their unique situation. Any claims that Joe Schmoe can break in — with a garage full of power tools and infinite time — are no more productive than the Lock Picking Lawyer’s videos, in which he always seems disappointed when a dollar-store padlock is defeatable by an angle grinder and carbide-toothed bolt cutters.

  6. Everyday security needs to stop two tweakers equipped with hammers, prybars, and a stolen cordless tool. A well secured safe or job box is beyond their skills or drive. As an aside, secure your power tools lest an opportunistic house breaker opens a safe using your own grinder.

    For concrete, wedge style rock bolts usually are stronger than residential floor slabs.

  7. Uh, picking nits here, but a terminology question:

    You said: “…2-1/2×3/8 in lag bolts through the holes, set a 1/2×2 in fender washer, then a 1-1/2×3/8 in fender washer, then a 3/8 in nut with red Loctite,…”

    I’ve never seen anything remotely resembling nuts for lag bolts.

    Do you actually mean hex head cap screw instead of lag bolt ? A lag bolt is designed to be screwed into wood and is commonly available only in Grade 2 (mild steel, aka “stove bolt”) strength, although Grade 5 lag bolts are available. Cap screws have specific thread-per-inch counts and come in either cut thread or rolled thread manufacture (SAE counts being either 16 or 24 threads per inch for 3/8 nominal diameter, Metric thread counts range from.50 to 1.75/MM), and cap screws are available in Grade 2 (generic hardware store/home center bulk bin stuff), through Grade 12 (Grades 5 and 8 are the most commonly available).

    As for the exercise described, the only changes I would make have already been covered: larger, custom-made “washers” (I did much the same thing once for a different situation, using doubled 2.5″ squares of 1/4″ mild steel plate as “washers” and 5/8″ Grade 5 rolled thread hex head cap screws, aka “bolts”), and run the bolts from the bottom so the nuts are inside the safe. True, thieves would have to know how it was done to attack it, and have access to the tools to do so (I assume you lock your tool box(es) when you’re not there to deny intruders burglary tools) but given the substantially increased police response times we’re seeing, I’d want to increase the Degree of Difficulty to the maximum conveniently possible.

  8. How did I miss this post 😛

    All good advice.

    And yea for those wondering Craigslist or Facebook market place is wonderful for used safes. I found a 3000lb double door safe with a 3hr fire rating (actual ul rated) I could have got derived to my house for $900.

    And as long as you know the combo or the door is open it is very easy to reset the combo of most locks. You either dial the new one if you know the current combo or your buy a $20 tool off of eBay to release the clutches and dial in your new combo is you don’t know the old one.

Only one rule: Don't be a dick.

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