I have a question that has been in the back of my mind for a very long time and may or may not be easy to answer. What is the purpose of the ditched pawl or ditched bow or anti-shim notch that seems to be one of the features of a quality cuff. When I got my first "real" pair of handcuffs I thought it was that if the hinge pin was defeated it would keep the swinging bow locked in the lockcase but I keep reading of how it is a anti-shim feature. It would seem quite difficult to shim vertically down alongside the bow and catch the pawl, especially if one was wearing the cuffs, although I admit to never having tried. Also, why did Peerless give up on the anti-shim notch at the end of the toothed portion of the bow? I know first hand how it complicates a normal shimming attack. Maybe they don't arrest enough escape artists.
As Tim noted, the pawl ditch was added to the Peerless cuff to strengthen it, as detailed in the 1915 patent (#1157135) covering the same.
The anti-shim notch first appeared on the Model 3 Peerless, and was covered by its 1932 patent (#1872857). As you probably know, the double lock feature of swing through cuffs works by locking the ratchet into place; as such, when double locked, it can't be shimmed. In this patent, the reason stated for including the anti-shim notch was to give a degree of protection in situations where the cuff had not been double locked. The patent narrative of this is somewhat critical of cops who failed to use the double lock feature, but it was a reality they attempted to remedy. In a way, at the time, failure to double lock was perhaps understandable. On the Model 1, double locking was done with the key and was awkward since to engage the double lock, you had to run the key through the unlocking portion of the lock. On the Model 2, double locking was simplified by using a push pin. However, the Model 2 lock had a distinct tendency to gum up with grime causing it to be extremely difficult to depress the push pin. On many of the Model 2 cuffs I've gotten over the years, I had to use a hammer and punch to get the pin free and working easily again. The Model 3 used a different push pin mechanism that was easier to depress (the Model 2 was pretty stiff) and not so prone to gumming up.
Around 1950, when Peerless began manufacturing their cuffs in house, as Tim observed, they undertook a number of cost cutting measures. In addition to eliminating the anti-shim notch, they stopped stamping their logo on the cuffs and changed the way the dog that engages the pawl ditch was created. Previously, on the Model 1, Model 2 and Model 3, the pawl dog consisted of a pin pressure fitted into a shallow hole drilled into the inside of the cuff body. On the "revamped" Model 3 they created the pawl dog by merely pressure stamping it into place, creating a corresponding detent on the outside of the cuff body. By this time, presumably, double locking of cuffs had become standard police practice which eliminated the reason for having the anti-shim notch in the first place.
