TJS, Old guys like me, and apparently like Paul B (no offense, Paul!), have been exposed to this stuff.
I think Paul was very prudent to advise against this. I was holding off answering till I saw what others said. The problem isn't in the brass, apparently, but as Paul said, in mistaking which .38 brass is really loaded to .357 specs. It's not enough to mark just the box it's in, because, what if you're carrying two boxes and drop them? Never happen? It happened to me with .44 Mag cases loaded to different levels--it was a crapshoot as to what case contained what powder charge. The plastic boxes shattered and a 100 cases were dumped on the cement garage floor. Duh!
If you could find a fool-proof way to mark those cases so that you and others wouldn't fire them in a .38 Spl. gun, it would be okay, maybe, but how we gunna do that? In fact, that's why .357 Magnum cases are 1/10" longer in the first place; it's a fail safe effect.
No one should take anything for granted when it comes to ammo. I have some 180 gr. LBT gas checked .357" bullets which must be loaded in .38 Spl. cases if there're going to be fired in my guns--they're just too long to chamber otherwise. I try to load and shoot them in the same day or two because of the danger involved. I'm certainly not advising anyone else to load .357 type loads in .38 cases--I wouldn't do it if I were you and I will stop as soon as I shoot these bullets all up. Not long now.
To top it all off, it will screw up your powder charges. You have to reduce the amount of powder in such "off-breed" loads because it's the equivalent of seating the bullet 1/10" deeper. If that is done and the charge isn't reduced appropriately, you could double SAAMI approved .357 Magnum chamber pressure!! You just can't be too careful. My advice is , "No."
[This message has been edited by Rod WMG (edited September 27, 1999).]