Greenslade
I remember those brass firochi caps no 11 they took a good strong mainspring to get them to go and they were a very hot .I do remember one unhappy result with them ,a friend who was with me had a early Pedersoli sxs percussion which had a weak main spring on the left hand lock which did not fire the cap ,returning the hammer to half **** he remove the cap but the cap compound was imbedded on the nipple top and what he did gave us both a big shock to remove it from the nipple using his finger nail and off the gun went some thing I had never seen before or after
Feltwad
Maybe that was considered a "hang nail fire"!