If your #38 has the Three-Letter prefix you are good to go for +P ammo. If it is one of the earlier versions you MAY get by with limited +P use but I would not use it if it were my #38. Others I'm sure will disagree but I am only referring to what I would do. I have shot older steel-framed J models loose with heavy loads so I am more conservative nowadays. Two or three times a year I shoot the loads that have been in my handguns and replace them with fresh ammo. That's about all the +P use my .38s get. Others may need to practice more to improve their proficiency but I can hit a playing card at 15 yds shooting DA with my carry ammo so I consider myself good to go. Practice with non +P ammo and save your +P for carry use and occassional practice in any J-frame that you care about.
Best Regards,
ADP3