I recently aqquired a 10-5 that had been locked in a safe for about 15 years. When unloading it I found 2 of the chambers were loaded with 38 S&W cartridges the rest were loaded with 38 special. Question 1 can the 38 S&W cartridge be shot from this model? Question 2 Is it safe to use 38 +P in this gun.

Your Model 10-5 should be used with .38 Special ammo.....I shoot +P's in mine on occassion.....and keep all of my .38's so loaded while carrying....plinking/target shooting I use standard loads....

rick

As you have observed already, some .38 Special revolvers will chamber some .38 S&W ammunition. Where a .38 Special charge hole is nominally no larger than .3806", they can, rarely, run as large as .3846". A maximum .38 S&W cartridge is ca. .386", minus .004. So, if your charge holes are toward the high limit, and the .38 S&W is on the small side, the .38 S&W can be fired in that gun. As long as the cartridge does not have to be forced there is no harm in shooting it in a .38 Special revolver.

Of my 20+ .38 Special and .357 Magnum caliber revolvers, 12 will chamber some of the .38 S&W ammunition I have.

That said, buy .38 Special ammunition for your guns, it is far more available, and a lot less expensive than .38 S&W ammunition. There is absolutely no logical reason to shoot .38 S&W in either a .37 Special or .3357 Magnum revolver unless you got it free!

There is absolutely no reason to not shoot .38 Special +P ammunition in any steel S&W K-Frame revolver that is model marked.