BEST lock information
A2 is the most common system that you will find. Like previously mentioned, the MACS is 9, so you can in theory do a 9090909, but it wouldn't really be recommended. Putting a 9 and then a 0 is fine, but it is advised not to do a 909 in the biting. There are 10 depths 0-9, and you use a 2 step progression. Also, the control should follow the same even odd format as your change, and masters. IE: Master: 2459823, Control 4671245. Now mind you this is not necessarily an ideal Master to Control, but is used to indicate that you should use all Even or All Odd in the same chamber. Many people don't do this. It is good to keep one chamber, say the first where all of the working keys never share the same cut as the Control. If you do, you could run into a situation where a change key would be cut the same as the control.
There are 2 other systems that can be used, although quite rare.
A3 and A4.
A3 is 0 to 6, for 7 depths. This system is single step progression.
A4 is 0 to 5, for 6 depths. This system is single step progression.
I had a few cores that are pinned to A3. Cutting keys on a HPC 1200CM was fun, since the default card is for A2.
If you turn the plug so that the holes are not in alignment with the rest of the core, when you load the pins, they pin stack will be almost even with the top of the core. This is a way to make sure that you didn't miss or add a pin. Then, turn the plug, and let the pin stacks fall all the way down.
There is a difference in springs. Some are for Falcon, and some are for Best. The Falcon springs are longer, and if you use them in a best core, and cap it, it is very difficult to get the key in, and can pop the caps out.
If you are in a pinch, and don't have caps, you can use .015 master pins from a standard pin kit. They are about .004 larger in diameter than the pins, and will drive into the top of the core just like the regular caps.
Of course we are all familiar with Master keying, however, you can masterkey at the control level as well. I had always wondered about it, and new that theoretically it could be done, then one time had an interview with Best lock (a long time ago, and the person interviewing me did confirm that it is possible, and is done in a few very certain circumstances. He did say that within Best, very few people understood the idea on how to do it.
Number 4 top pins will many times flip on their side. If you use an ejector tool from beneath, and raise the pin stack, and then put in the master pin, you can more easily put it in the chamber, and keep it flat.
The W Keyways, IE: WA, WB, WC, and such are NOT restricted. Confirmed that with Best directly at this past ALOA show. They are not common, but not restricted.
The coremax keys can have 4 different depths of millings. Many times if a key sticks, maintenance will rap the key with a heavy object. Doing this with Coremax can damage the slide, and lock up the core, requiring the core to be completely drilled out. A major pain in the neck. Coremax come in a restrited set of keyways. Those are extremely restricted, and are only sold to the certified end user. They start with an X and then 2 numbers. Each "Family has 4 keyways available, and then there are composite keyways for the first two, and last 2, and then one composite keyway that fits all 4. Example X11, X12, X13, X14 are the regular keyways. Then X15 covers X11 and X12. X16 covers X13 & X14. X17 covers X11, X12, X13 & X14. In standard keyways, they do not offer Coremax on A, B, C, D, E, F, G, or H. They only have them in J, K, L & M.
It is strongly recommended to not having repeating numbers on any keys. You would think that would make sense, but I once worked on a system that that the control was 4444444. Yikes!!.
There are some old 5 pin cores out there that were in padlocks or drawer locks, and the lock body would only accept a 5 pin core. Had one that needed replacing, and had to get it directly thru Best.
As mentioned elsewhere, sometimes you will see a 7 pin core with the last chamber (at the front of the core) is empty. That can be due to the system being setup as a 6 pin system, but only 7 pin cores are available.
I have thought that you could do a system where some of the chambers are A2, some are A3, and some are A4. It would be a bear to reverse engineer, not to mention a bear to maintain, but it would be an interesting way to mess with someone if they wanted to try and figure it out.
While A2 is the most common, A3 can provide more changes under a Master.
A2 - 10 Depths - 2 Step Progression - 5 usable cuts - Subtract 1 for the Master - 4 Useable cuts for progression. Progress in 4 positions = 256 Changes
A3 - 7 Depths - 1 Step Progression - 7 usable cuts - Subtract 1 for the Master - 6 Useable cuts for progression. Progress in 6 positions = 1296 Changes
Hope this info is helpful.