Ultimate Guide to Gun Safe Inner Steel Liners (Upsides & Downsides)

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Inner steel options (also known as steel liners) have quickly become essential to help manufacturers stand out from the pack. Fort Knox is the most prominent manufacturer that offers this feature. However, prominent brands include Amsec (American Security) and Vault Pro.

What is a gun-safe inner steel liner?

Fort Knox Defender 6637
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Inner steel creates a safe within a safe. Let’s take a Fort Knox Defender example; the Defender series comes standard with ten gauge steel; while impressive, it is not the highest gauge steel in the market.

If a standard inner steel liner (in the case of the standard carbon steel, an additional ten gauge liner) is added, it creates a complete steel safe within a ten gauge steel safe. 

This means that if someone with a grinding wheel can cut a hole in the side of the gun safe, they must cut through a new layer of steel with only a small window to work with. Fort Knox’s Defender series offers many inner steel options, such as AR500 ballistic and stainless steel (which dissipates heat).

Why are inner steel liners a great thing to add to your safe?

1. Inner steel allows for a great value.

Many manufacturers require you to upgrade to a higher series of safes if you want a more significant amount of steel. Although the issue with this is that a higher series generally means a customer is paying for a higher level of luxury, not just steel gauge. 

Take the Medallion series of Browning. If a customer wants the Medallion but wants seven gauge steel, they would need to upgrade to the Platinum Plus series.

However, this upgrade has a more expensive interior and other luxury options. Companies that do not offer inner steel options don’t allow for an upgrade of steel for a minimal cost, and the customer is now required to pay for something that they never wanted in the first place.

2. The flexibility of inner steel

This option does give the flexibility that is needed to give you the safe that you genuinely need. There are many different options of steel types to choose from to be added to your safe. 

  • Standard carbon steel is the most popular and creates a safe within a safe of the same steel. 
  • Stainless inner steel keeps determined thieves from cutting through the safe quickly using grinding equipment or cutting torches, as this type of steel dissipates heat quickly, keeping the melting point low for these tools.
  • Then there is AR500 ballistic steel from Fort Knox. This type of steel can withstand blunt force hits, such as from a firearm. This is the same type of steel used in police bulletproof vests.

What are the downsides of inner steel liners?

1. Inner steel adds weight.

With ten gauge steel being the minimum steel that can be added as an inner steel liner, this option can add quite a bit of weight. This heavy-duty steel gauge benefits security but limits you considerably if you want to keep your safe weight lower. 

That said, a significant portion of the weight of your safe is with the fire rating material, so it won’t exactly double the weight of your safe, but it will likely add around an additional third to the overall weight instead.

2. The option minimizes your brand options.

Liberty Safes
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Inner steel liners are limited to a few select brands, and this is only one way to maximize the security of your big steel box. Limiting yourself to these brands might make you look away from other notable brands offering other features, such as easy access to firearms like this brand, a modular gun safe design, or one of the best warranties in the business with companies like Liberty Safes.

Frequently Asked Questions


Inner steel liners are one of the best ways to make a gun safe and more secure from attacks like grinders, cutting torches, and more. It is also one of the least expensive ways to do this, as you don’t have to upgrade other luxury features to make it happen. 

That said, it can add a lot of weight to your safe and minimizes the number of brands you can choose from. Regardless, this feature should be considered for our next safe!

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