Strange occurrence with an SFIC

[phrygianradar]

I have been picking SFIC locks for my local locksmith for a while now. I have opened about 15 or so of them for him, and the deal he made with me is that for each one I can open, I can keep one. So, one for one. They are mostly old junkers that come off old doors and such, but every now and then there are a few nice ones. It is good practice for me and I have really been enjoying the challenge of opening these without the aid of a key to look at.

So anyway I have a bunch now, but I only have one core decoded and I got a padlock to put it in. It was the first one I ever picked; an Arrow 7-pin. From the very beginning I had seen another lock in his store; a Best padlock with a 6-pin Master(brand) SFIC core in it. So today I came in and traded in four of the ones I had picked for some locked keyless ones, but decided that I wanted to buy the Best padlock as well. I thought it may be handy at work.

Now for the weird bit. When I got back to work I started trying to pick the cylinders I had gotten. I noticed that one of the Best cylinders had the same keyway (Best A) as the Master core in the padlock I had also purchased. Since some of the cylinders I get have crumby springs or stuck pins I decided to put the Master key in the Best core. I put the operating key in and jiggled it, then I put the control key in to do the same only to discover that it actually worked in the lock! Not as a control key, but as an operating key! I was dumbfounded. I still don't know what to make of it...

I don't see how it is possible for the control key of one core to work as an operating key in a random cylinder that is from who knows where. Could it be just a crazy coincidence? The odds would be astronomical.

[LockDocWa]

SFIC cylinders have many master pins in each cylinder.
The more pins you get in a lock, more shear lines are created.
However unlikely it is for you to get lucky enough where a random key acts like a change key,
It isn't impossible. I would think, a randomly keyed Schlage with NO master pins,
would be harder to find a working key in a box full of random cut keys.

You mentioned you had to jiggle it to get it to work, It may be only a cut or two away from the real key.
By the way , congratulations on finding a key that works!

[2octops]

Just a crazy coincidence.

There are only so many combinations of pins.

It happens, most people just don't know it.

[phrygianradar]

Yeah, I think it was a coincidence too, although I am going to ask the guy who gave it to me anyway. I'm sure he will be interested to hear about it. Thanks to all who put in their 2 cents! I had no idea this could occur, I thought there were so many combinations of key cuts that could be made that this sort of stuff just couldn't happen. Not the first time I've been wrong, not the last time I'll be wrong!

[2octops]

Heck I've been out on a call to rekey a property, made up the new key with random numbers outta my head and it turned out to be the original key that fit the locks in the first place.

It happens.

[LockDocWa]

I was rekeying an Elks Lodge one time,
I use my house key to unscrew mortise cylinders.
My house key worked the lock, That cylinder was master keyed.

Yep, if you try enough random keys in locks, you will eventually find some that turn.
Isn't that the basis of try-out keys?

[Sinifar]

BEST "A" keyway is not used by the factory much since about 1945, but still used by locksmiths.

Most Best today is the "J" - "K" - "L" - "TB" - "TC" - "TD" - "TE" and a few of the "W", like "WB" - "WE" - "WH". Best also has their own Peaks, "B-1" - "B-2", which you won't see, or get blanks for.

Having said that - YES sometimes a working change key / master key might pull out a core. It depends on how "close" the control is to the lower set of pins, if you know how to do the "math" - then you would understand. Having a lot of "10B" pins in the set for the control is going to cause problems, as 10 is .125 which is the thickness of the control "slug". SO A LOT of 10's in the set will cause this to happen.

ALSO new cores can be "tight" and working the change keys / master keys might "pick" the control shear line.

A worn out core will also allow you to jiggle the thing enough if the control is close pinned to pop the thing out. Which is why "A" is not used much, it is too "wide" and not enough side milling to keep even a worn out one from doing that.

A2 or A4 pining makes no difference, there is the same relationship between all pins sets and the cores they go into, as there is no special core for either one. SO this can happen if you are not careful in selecting your control key bittings.

Sinifar