>The description says nothing about "chopping". It says "cutting and prying out the waste". Having never used a lock mortise chisel, I can only imagine its utility for deep mortises; i.e. you chop across the grain with a straight mortise chisel and then cut and pry out the waste with the lock mortise chisel. Again, having never performed this operation, this is just how I assume it would be used.
>I just installed a lock mechanism in a solid wood door for a client.This thing required a mortise 4" deep,7/8" wide by 6" long. I drilled out the bulk of the wood to about 3".Squared the ends and cleaned it with a 7/8" mortise chisel and a wider parer.This last part took the longest. I carefully chopped a series of cuts from one end to the other,scraped it clean and measured,repeat,til I reached my depth.I did manage to get a clean flat bottom(very important as I was very near the glass in the door)but it was tedious. A lock mortise chisel would have been the right tool for the job.I too have seen old doors hacked out to fit those rectangular lock mechanisms but this was a precision fit.---Jack