I am sure I missed a few, but here are some of the differences between the new S&G 951 padlock and the 833C:
The 951 is the government version and is stamped “US Government Property†on the front. The commercial version is the 951C and it obviously does not have this stamp and uses a different top and bottom. With the 833C padlock, the only difference between the commercial and the government versions was the restricted cylinder.
The casting process has been refined and the body is very smooth and almost defect free. One example of this is that the bottom of the lock does not have the square casting marks around the keyhole like the 833C. The stainless alloy of the lock also appears to have changed, but I have not confirmed this.
The dimensions of the top and bottom have increased slightly and the casting around where the two parts connect has changed. When assembled, the gap between the top and bottom is larger than the 833C. If you took 5-10 833C locks and swap around the tops and bottoms, not all the tops would fit on all the bottoms without some force or filing etc… The larger gap of the 951 ensures that any top will fit any bottom (have only confirmed with 2 951 locks, but I am positive all will work).
The drill protection cap is thicker and has three hardened steel/carbide inserts embedded in it.
The 951 Medeco cylinders actually use several ARX features!!! It has ringed micro-milled, ringed milled, standard (broached), and milled bottom pins. It is very rare to find an 833C cylinder with even one milled pin. The plug also has a carbide rod running through the entire length of the side opposite the sidebar. The rod is kept in place with a setscrew. The front and back milling of the plug remains the same.
The type of ceramic used in all the inserts has changed. The orientation of the inserts has also changed. The number of inserts has not changed.
Serial numbers are engraved on the inside of both the top and the bottom.
The commercial version retails for $2266.
There are no patent numbers anywhere on the lock.