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Fort Knox Gun Safe with S&G 6120 lock sometimes doesn't open. My Solution

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I have two Fort Knox gun safes with Sargent and Greenleaf 6120 electronic lock. Sometimes they fail to unlock on first attempt. I've considered making two thread topics: one for the safe container boltwork and another for the lockbody. However, they lock and boltwork must be an integrated single system.


1) The lock is pre 2013, thus is not certified for EMP resistance. The specified deadbolt motor retraction force is 50g (about 50 paper clips). If there is any tiny amount of side load on bolt, it will not retract. I removed the 6120 from the door and attached a 100g weight. I let the lock cool down out side at 44F to weaken the battery strength. The lock did lift this weight thus surpassing the mfg's specification. My conclusion lock by it self works fine as long as nothing touches the retracting bolt. The locking bolt has alot of side to side movement with minimal finger pressure. Bolt's width is 0.90"


2) The safe's boltwork has a disk with geared teeth and a cut slot for the boltwork to insert and block disk's rotation. This slot is 1.05" Boltwork has two adjustable hard stops so that locking bolt can be centered into disk slot. Depending which orientation i let the handle rest, sometimes the locking bolt touches the slot and prevents unlocking. This annoys and frightens me.


My solution: I wanted some type of detent that would hold the container's boltwork off of the lockbolt, thus ensuring an unlock every time. I considered adding a spring loaded detent, cable with mass, or magnate. I eventually decided to use some 1"diameter 100 pound force magnates to pull the boltwork all the way to hardstop. After multiple iterations, i found a location to install a bracket that has no pinned linkages. The pinned linkages have too much backlash for the magnate solution. Once I settled on my bracket location I reinstalled the lock only to discover the side to side movement of bolt was still too much in the slot. Phase two was to remove the disk, hold in my bench vise and grind the slot to 1.09". Now when boltwork is close enough so that lockbolt engages, the magnates will pull the slot into perfect alignment with zero contact ensuring my safe opens first try. The handle always returns to the same position after I remove my hand. 


It was quite the project while learning. I expect the second safe to be modified in less than 4 hours. I hope this info inspirers someone to tune up their safe. Life's too short to put up with preventable failures. 


I would like to upgrade my lockbody. I had seen the electric battery free Kaba Mas Auditcon 52. The "generator aka power star technology" had my interest. These have a wide temperature range, but no EMP certification. The vertical deadbolt with manual retraction spindle would work. I'd like the automatic re-lock feature of a swing bolt, but my safes have left handed boltwork and I can't get an answer if the swing bolt is reversable and allows a relocker plate on front side..... So now I'm thinking, I want to install the SecuRAM Extreme (mechanical and digital). It has a swing bolt (auto relocks) and an adapter for left handed boltwork. Does anyone have experience with this or another model of electronic+mechanical redundant lock? Honestly I'm not woried about EMPs, but want the redundant unlock feature. This lock has a mechanical spindel that will allow much more than 50g of retraction force if needed. (Maybe the hardstops go out of adjustment some day).


p.s. Admins, if this topic belongs elsewhere, please move it. 



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  • 5 weeks later...

Thanks for sharing your findings OP.  If I decide to get a safe with an electronic lock, I'll keep these details in mind.


For now I'm sticking with mechanical S&G locking mechanisms.  If you have more than 1 safe, there's a small key/tool that you can buy that allows the combination to be reset, thus allowing all safes to have the same combination if desired.



Edited by muncie21
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