I have a whole box of Fiocchi .45 ACP with small pistol primers.  Never reloaded em, and probably never will.

I suspect as Butlersrangers stated, the primer pockets on those Western 29 cases were crimped.  I wouldn't use the pistol primers either.  I would just abandon them and order some Hornady or GRAF brass instead.  You might get away with shooting them, but given the age and primer issue, you'd be taking unnecessary chances... and (much) better brass is available and plentiful!  FWIW, Pistol and Rifle primers are different sizes for a reason.

If you really want to get confused, with Berdan primers, there are no less than 9 different sizes!