Hollon FB-450E 2 Hour Fire and Burglary Safe - Electronic Lock no-sales-365 and the internal volume is

and the internal volume is 15

so if your gun safe door is within a few inches

Inside Dimensions: BWB2020: 9

The Hollon TTW-2015 C/E Through The Wall Deposit Safe features a 1/2” steel door

It is a steel security safe that weighs 31 pounds

Hollon FB-450E 2 Hour Fire and Burglary Safe - Electronic Lock no-sales-365 and the internal volume isHollon FB 450E 2 Hour Fire and Burglary Safe Electronic Lock Built with security and burglar protection in mind, the Hollon FB 450E features heavy duty hinges and a unique 1" thick hinge side locking bar that extends from the top to the bottom of the door. Plus, it comes with a 2 hour fire rating standard and tested at an outside temperature of 1700 degrees F. This safe truly is the best burglar and fire protection money can buy. The Hollon FB 450E