Hello, Doc Hoy. I too experienced mis-fires with a Colt S.A.A. This one is in .38 Spec. gun had action/trigger work by Hamilton Bowen..hammer pull really lightened up. Funny thing, on those that did go off..punch mark on primer looked to be normal depth & dia. I have always seated primers by "feel"..using the excellent K&M tool.
Not wanting to go thru all the hassel & potential risk of shipping gun back..I remembered my Forester Co-Ax press has a built-in priming feature..and priming punches have a built-in pre-set depth control of .002" under case head. I began priming using this tool..and have not had a mis-fire since...you can really see difference in depth between the two priming systems. I still use the K&M for everything else..rifle & revolver..just not for that particular Colt.