I would not. Extra case space and small amounts of powder may result in incomplete burn. Incomplete burn sucks, not only in terms of inconsistent loads but in terms of filth and unborn powder in the nooks and crannies of the gun which can cause malfunctioning.
Load 38 using 38 recipes and 357 using 357 recipes. If there happens to be some overlap, go ahead but don't just assume it'll work.
The 357 cases are actually longer than the 38 spcl...so you'll have to reset your dies for them. I've crushed a few cases forgetting.
I found a good set of used Lee dies. Looking for a second set now. I have no problem with a set for each round...saves setup time, just my humble opinion...
I have reloaded for my .357's since the mid 70's, and never owned .357 dies. I would not worry about separate .357 dies. If you really do not want to screw your die body lock ring settings the .150", RCBS and Redding (and probably others) make a calibrated spacer washer kit to make the settings on .38spl dies work with .357 cases.
I have reloaded for my .357's since the mid 70's, and never owned .357 dies. I would not worry about separate .357 dies. If you really do not want to screw your die body lock ring settings the .150", RCBS and Redding (and probably others) make a calibrated spacer washer kit to make the settings on .38spl dies work with .357 cases.