Locksmithing/Mosler 302



I recently purchased a Mosler class 6 5-drawer security container surplus, which came equipped with a Mosler 302 group 1R lock. The combo is known (standard) and the lock seems to be in good condition; has a smooth action and reliably locks/unlocks. I am wondering if I should consider replacing this lock? I'm sure this cabinet/lock was in a high use environment during its service life, and I'm concerned that some of the internals might be worn and result in lock failure with all my items securely inside. I know some of the anti-tamper/anti-radiological high security locks used composite/plastic parts that become brittle and fail over time, is this true of the 302?  I do not know the date of manufacture, but it has 'BP-800' and 'B-61398' on the label (if that means anything to you?). Would you recommend that I replace the lock, or change the combo and go? If you recommend replacing, what lock do you recommend? I know Big Red makes a exact replacement for the Mosler 302 (which I think is a group 2), any thoughts on this lock?




As Mosler has been out of business since 2001, pretty much every thing with their name on it is going to be at least 13+ years old.   Chances are your lock is at least as old as the container.   Check the data label on the operating drawer to see when the container was made.

As far as replacing the lock, my first question to you, is are you required to use this GSA container as part of your business???   If the answer is yes, then you are limited in the locks that can be installed.   If the answer is no, then you can basically put what ever lock that you want on it.   However, please note that if ANY modifications are made to the container to use another lock, the container will lose is GSA label.

The "Big Red" locks are an inexpensive knockoff of the S&G locks.   As GSA containers are NOT easy containers to open, I would recommend installing a quality lock.   Spend the extra money so you don't have a problem.   While the Mosler MR302 was a group 1 lock, the Big Red is not.

Last question, hopefully you didn't purchase (or acquire) this container to actually use as a safe.   The US Government looks at security a lot different than the civilian market does.   GSA containers are NOT designed to provide any real level of security.   The walls of the containers are made from thin sheet steel, which can easily be cut open in a burglary.
The government doesn't really care about burglaries, AS LONG AS they are able to tell that the container was forced open.    ALL of the protection is around the lock, to provide protection against covert and surreptitious methods.
Unless this container is also rated for fire resistance, then it offers none.
Civilian containers are designed and rated in their ability to protect your contents from fire and/or burglary.

So before spending ANY money on the container, you need to answer the question - what are your plans for it, and/or your expectations.

---------- FOLLOW-UP ----------


Thanks for the quick response. I plan on using this container the same way Uncle Sam did, as a secure filing cabinet (for personal use - GSA rating not required). I needed somewhere to store my old taxes, bank records, etc that no longer fit in my desk, and the GSA container was cheaper, more secure and has more capacity than the stuff at Staples...so here we are. Understand that a burglar with a crowbar and hammer can have it open in a short while (as there is no forced entry requirement).

My main concern with the lock is that it will fail due to age/ware, and force me to mutilate the container to get my files. I am however, becoming less concerned with this as I have locked/unlocked the 302 (with the drawer open) many times without any issues, and the action is smooth. I did remove the back panel and took a look around inside. I did not see any excessively worn parts, and the plastic wheels seem to be in fine shape (but then again I'm not a safe tech). Cabinet was made in Dec 1988, so based on your comment the lock may also be 26yrs old. This lock is a MR302, so it requires hand combo changes.

I would prefer to keep using this lock as group 1R (even an obsolete one like this) provides plenty of protection for my needs, rather than invest in another lock with lower rating (likely group 2). I saw in some of your other posts that you have provided the change procedure in the past...could you provide that? I understand that there is the danger I will damage the lock, but if I do I can replace the lock, so there doesn't seem to be too much down side (other than paper-weighting a MK302). Also, is there any general preventative maintenance guidance you could provide for this lock?

Thanks again.



As far as providing the changing procedures for your lock, I'm assuming that you have an MRK-302, which is a key change version.    Problem is as Mosler has been out of business for over 13 years, parts, including change keys are becoming difficult to obtain.

I'll have to check to see if any are available.   One of my suppliers does have it listed in their catalog, but I'll have to see if they actually have any and what the price is.    Please send a request to me at:    andy@securitysafeusa.com    to request it - otherwise I'm not going to remember you are looking for it.

If you have the MR-302 hand change variety - again, send a request to me and I'll send you the instructions - though as this requires partial disassembly of the lock, I DO NOT recommend this as a DIY project.  (see service comments below).    I also have a hold harmless form that you will need to sign to receive the instructions.   Basically it just states that YOU assume all responsibility for the use or misuse, and/or interpretation of the instructions.

As for whether or not the lock will last, I would recommend having it serviced on a regular basis to ensure operation.     
NOTE:   I NEVER recommend servicing as a DIY project for the same reason that I never recommend using locksmiths for safe work.    Lack of training, knowledge and tools can easily result in an expensive lockout.    For a GSA, Black label, Class 6 container, you could easily be looking at $1000 plus parts if it doesn't open.
Similarly, if you elect to have the lock replaced, regardless of what you have installed, it should be installed by a safe technician to ensure operation, and to provide you with some type of service warranty.

As far as general service maintenance - sorry but I don't get into this.   My basic service class is about 1 week long, so I don't even attempt to go over it on a forum like this, or even as a follow up question.    Nothing personal, simply not enough time or space.
If you need it serviced, I recommend your having it done by a safe tech from a local safe company.  


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Terry V. Andreasen (Andy)


Safe and Vault related Questions; Antique Safe Repair and Restoration; With over 42 years in the Safe & Vault industry, if I can't answer your question I know where to get the answer. Current Project: Restoration of an Ely Norris Cannonball Safe from the early 1900's. Will answer Safe & Vault related questions concerning age, value, restoration, moving, opening & repairing, parts, operation and history. Note: It is not my intention to teach you to open safes or to provide information which may aid in the unlawful opening of a safe. I will not give out drill points or information which I deem inappropriate.


44 years in the Safe & Vault Industry. Owner and Service Manager for one of the largest Safe & Vault companies on the West Coast. Graduate of Lockmasters Safe Lock Servicing, Safe lock Manipulation and Safe Deposit Lock Courses. Graduate of Locksmith Institute. Certified Instructor for the California Locksmith Association teaching Basic and Advanced Lock Servicing, Basic Safe opening and Repairing. Factory Trained by AMSEC, LORD Safes, LeFebure, Mosler, KabaMas, LaGard and Sargent & Greenleaf Author of "The Coffee Table Guide to Antique Safes".

SafeCrackers International and the National Antique Safe Association Safe & Vault Technicians Association (SAVTA)

The Coffee Table Guide to Antique Safes AllExperts.com

Graduate of Locksmith Institute 1972 Graduate Lockmasters Safe Lock Servicing 1974 Graduate Lockmasters Safe Lock Manipulation 1975 Graduate Lockmasters Safe Deposit Lock Servicing 1985 Instructor Certified - California Locksmith Association - 1985 Factory trained by AMSEC, MAJOR, STAR, Johnson-Pacific, Kaba-MAS, Allied-Gary, ISM, Lord, Brown Safe, EXL, Mosler, Diebold.

Awards and Honors
2009 - 2015 - Listed in AllExperts Top 50 Experts. All Expert Categories - Safes & Security Containers, Locksmithing, Antique Safes. Retired US Army Chief Warrant Officer (CW4), with 39 years of total service. With numerous awards from Vietnam, Desert Storm and Operation Iraqi Freedom. US Navy - 1971-1981 US Army Reserve 1984-2013 US Army Retired

Past/Present Clients
US Secret Service, FBI, BATF, Local Law enforcment agencies, Diebold, Hamilton Pacific, Red Hawk Int., Chubb International, Bank of America, Wells Fargo Bank, Mechanics Bank, El Dorado Savings Bank, many Credit unions and smaller banks. McDonalds, Togos, BurgerKing, TacoBell, Carls Jr. FoodMaxx, SaveMart, Lucky's, Albertson's, Raley's, Safeway, NobHill, Bell Markets, PW Markets. Great America, Century Theatres, Cinemark Theatres, UA Cinemas, and many homeowners and small businesses. Provide warranty service for lock and safe manufactures. Service Area is Northern California (Fresno to Oregon and Western Nevada)

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