I am purchasing a building to move my business into (gun store). The building is currently an empty shell. Wood framed with metal sides and roof, 7000sf. I'm going to have a 12x10 walk in vault built. Most likely out of concrete blocks with rebar and poured concrete inside. Would it be best to have the vault built on an exterior wall or more centralized inside the building?  Ideas for protecting against fire?  I will have some HVAC and electric built in. Should I do a floor drain as well?  Is there some sort of one way valve that could be put in the drain that would keep it from ever backing up?

The fire department has told me that should my business ever catch fire, they will only try to control it from the outside and prevent it from spreading to other buildings. I'm thinking a road side exterior wall would be best, so at least the general area could be hit with water from outside.

a concrete vault with a concrete floor and roof will need to have 4 sides and a lid. I would build it in the center of the store.
You wont have to worry about it getting too hot, until the fire leads to a building collapse.
Building fires are hottest near the walls, where there is ample fuel and air.

BTW, your FD will enter the building if there is chance there is a person inside.  They will also be punching holes for vents.

7000sf is pretty big.  Does this include a shooting range?

I came to say talk to your fire dept they will be the ones showing up if something happens .

I managed a shop just slightly larger than that. We had a walk-in safe at the end of the main sales counter a bit smaller thanyou are asking about.
Only one wall up against an exterior wall.
Building code would not allow a “vault” without spending a ridiculous amount of money. Like bank vault shit. Stand alone air ingress and egress, power, etc. a shit load of life safety issues. In our case not worth it.
However. We completed the safe within Code by not sealing it completely. Just another layer of protection if shitheads got in.

For some reason the insurance company cared more about added protection for repaired items than the couple hundred thousand in new stock ?

We had 3 large fire rated, stand alone gun safes for super expensive shit if needed. Rarely used them. Except for crazy expensive customer guns in for repair. Plus a Black Powder Safe on wheels that lived by the back door.
Everything is insured so ... ?

So...the only real reason for it was for excess stock of new handguns and storage of customers repair firearms.
The exterior (2 sides visible in show room)was covered in polished stainless steel and the door was 80% solid with 1” thick bars top and bottom to allow air to circulate in and out of the room. With a combination lock.
Building had 18’ ceilings. So we put a water resistant roof on the safe and then used the space above for display.

Building code will most likely be the obstacle?

Great points about the location and the FD, thanks! I've strongly considered doing an indoor range but with the upfront costs involved I think it would take a long time to see a ROI. So I'm only planning to occupy about 4000sf of the building. The rest will be left for me to rent out.

The shop is in Alaska... building codes are pretty lax. I don't think it will be much of an issue.  And wasn't planning to have any part of the vault visible for customers. You are correct, all the stock on hand and customer guns are covered by insurance. I mostly want it to store my collection of rare Colts and real high dollar inventory.

Then you should find a professional who works in Alaska that will know what they're doing.  Find out who does the vault work for your local bank and reach out to them.

Tagged...because I'm in AK also, and next year I'll start on my shop build, planning on a vault room in the shop building too.