It's unusual to find the Cobra in a 4" barrel, but Colt did make them. They also made it in 32 Colt New Police/32 S&W Long and 22 Long Rifle. I'd like to find one in 22.I don't own a Colt PP, but I do "own" a Colt Cobra. Mine is a vintage 1974, so it has the shrouded ejector rod. I say I "own" it because it actually belongs to my agency.
It was once carried by a former chief of police many, many years ago. When I first went to work here, my chief at that time had it in his desk drawer (he carried it for awhile too). I asked him about it and he said he would issue it to me if I so desired. I told him hells yeah, I so desire!