The medium frame Colt "E" revolvers like the Army Special can safely shoot +P .38 Special ammo, but much of it will cause faster wear.
There's really not much sense in overly wearing an antique Colt, but it can shoot a good bit of it.
In the pre-war days Colt had the standard of just marking revolvers with .38 no matter what the actual caliber was.
A .38 marked Colt could have been .38 Colt New Police/.38 S&W, .38 Long Colt, or .38 Special.
Much depended on the model, with the short .38 cartridges usually in the small frame models like the Police Positive, and the longer rounds in the medium frame models.