I had originally posted this some time back and did not bother citing the specific forum or poster though I did allow I had gotten it elsewhere as stated above. Wrong of me. So if that original poster if a member of or just wandering through, this forum, should happen along and recognize this, please accept my apology and thanks for the information and by all means claim the credit for it!
Just look at the following with the thought that I cannot personally vouch for the information.
"The .38 Long Colt was from 1875. The .38 Short Colt is just a shortened version used in the Army and Navy models of Colt revolvers. Both will fit and fire in a .38 spl. revolver as they are both shortened version of that case. The .38 spl. is too powerful to shoot in the older revolvers even though the cartridge may fit the chamber. The Long Colt has been obsolete for many decades, but as the Short Colt was used for military handguns you can still find ammo [for it](Remington). The .38SW has a different case (larger diameter) than the .38 spl. and generally won't fit in the .38 spl. chamber while the .38 spl. case would be too long for the .38SW chamber. The Colt .38 NP (New Police) is the same dimensionally as the .38SW and can be used as such."