It's not the size that I'm asking about, it's the tendancy of the caps to break apart into small pieces that cause the problems. The origianal Colts were recomended for use with caps such as Ely's Double Waterproof. These caps had a thicker copper to reduce the occurance of the cap breaking into fragments and tying up the gun. This apparently was a cause of some concern in that different caps were required for different guns. The caps generally available today are not the quality of the Colts type caps judging from the number of posts on various forums mentioning Colt type guns becoming disabled from cap fragments.
The matter was disccused in a letter from Major R.H.K.Whitely, writing from the New York arsenal on July 5, 1862, to Brigadeer General J.W.Ripley, Chief of the Ordnance Department in Washington.
'First, a cap suitable for Colt's pistol does not suit either Savage's or Starr's, because the main spring is too weak to explode it.
Second, a cap suitable for savages or Starr's pistol does not suit Colt's because the hammer drives it in pieces, a fragment often lodges in front of the cock, and renders the arm useless after the first fire...............Therfore, I am compelled to have two qualities made, onr for the Colt's answering in thickness to the Ely's double waterproof, and the other for Savage's and Starr's to Ely's metal lined.' Ripley forewarded the letter to Major W.A.Thornton at West Troy Arsenal and requested the he 'please see that all revolvers made for this Department are suited to fire the same caps as Colt's Army pistols.' From "Guns of the American West" by Joseph Rosa.
30-some years ago I recall using differant caps that had varying characteristics, some would fragment badly, some would ballon out and split, but not fragment, and some would stick on the nipple badly, making reloading tough, as the caps had to be removed from the nipple with a tool.
My question is, is there a cap available today that does not break into small fragments and tie up Colt's type guns?