I just read this for a Class I:
GSA Class 1:
a GSA approved container meeting Federal Specification AA-F-357(canceled) with entry protection consisting of 10 Man-Minutes forced entry, 30 Man-Minutes surreptitious entry and 1 hour fire rating
Hell, you may be able to get a TL-30 for that price. AmSec's RF6528 retails for $8415 with textured paint. Which means you can probably get it for under $6K. It also weighs 3455 lbs. so make sure you have a good breakfast.
There is a big difference between a GSA Class 1 and GSA Class 5. Classes 1,2,3 and 4 are not even made any more as they are not authorized for use in the federal government for the storage of classified material or weapons
Here is the break down:
C. Classes of GSA Approved Security Containers.
(1) Class 1. The Class 1 security container is insulated for fire protection. The protection provided is:
30 man-minutes against surreptitious entry
10 man-minutes against forced entry
1 hour protection against fire damage to contents
20 man-hours against manipulation of the lock
20 man-hours against radiological attack
(2) Class 2. The Class 2 security container is insulated for fire protection. The protection provided is:
20 man-minutes against surreptitious entry
1 hour protection against fire damage to contents
5 man-minutes against forced entry
20 man-hours against manipulation of the lock
20 man-hours against radiological attack
(3) Class 3. The Class 3 is an uninsulated security container, and the protection provided is:
20 man-minutes against surreptitious entry
20 man-hours against manipulation of the lock
20 man-hours against radiological attack
No forced entry requirement
(4) Class 4. The Class 4 is an uninsulated security container, and the protection provided is:
20 man-minutes against surreptitious entry
5 man-minutes against forced entry
20 man-hours against manipulation of the lock
20 man-hours against radiological attack
(5) Class 5. The Class 5 is an uninsulated security container, and the protection provided is:
20 man-hours against surreptitious entry (increased from 30 man-minutes on containers produced after March 1991)
10 man-minutes against forced entry
20 man-hours against manipulation of the lock
20 man-hours against radiological attack
30 man-minutes against covert entry (added to containers produced after March 1991)
(6) Class 6. The Class 6 is an uninsulated security container, and the protection provided is:
20 man-hours against surreptitious entry (increased from 30 man-minutes on containers produced after March 1991)
No forced entry test requirement
20 man-hours against manipulation of the lock
20 man-hours against radiological attack
30 man-minutes against covert entry (added to containers produced after March 1991)
Class 5 is better than Class 6. What exactly is the thickness of the steel in the doors and body??? Depends on the manufacturer. Most Class 5 GSA safes comparable to a B or C rated safe in the protection they provide, though not necessarily in the steel thickness. Remember, a GSA Class 6 safe is probably going to provide better protection than any RSC out there, but it does not formally rated as having sustained a forced entry attack like a GSA Class 6.
Part of their rating comes from the requirement for a X-09 lock. That provides the manipulation proof features and the X-ray protection.
If you could get one at a good price, it may be worth it. The X-09 lock alone is over $500 at gov prices, several hundred more for civilians. X-08 is an older version of the X-09 that you may see if you buy it used. Unlike the S&G, LaGard and others, the X-09 is truly manipulation proof as it is an electronic dial with no batteries. It is the only approved lock on gov safes and vaults. The U.L. listed Group 1 manipulation proof locks are not authorized because the can be manipulated in minutes by a pro. Of course hopefully you are not planning for that.
But if you are paying full price, than you might want to consider a TL rated safe.
Edited for clarity