Bill: I'm starting to question the urban legend about square cut standing breeches being subject to cracking. This may be an engineering solution looking for a problem. Parker made guns square cut till about s/n 13000, which tells me it wasn't a problem in the 1870s, otherwise the gun works would have radised the joint sooner. Possibly there was a problem related to the early water tables narrowing toward the standing breech because this was changed quite early in the production run.
Documentation of failed/cracked actions would seem impossible, as any defect was fatal and the action would have been scrapped. I found one reference to Parker guns circa 1871/72 having "broken backs" made by a letters-to-the-editor writer named "Hazel" (nom de fusil), who was complaining about Capt. Bogardus's Parker being "shakey at the joint." but Bogardus wrote a letter saying it wasn't, and praised the Parker. Then he shipped out for England and started shoting English guns. EDM
