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I'm sorry to hear of the loss of your Dad, 450mar (and welcome to TFL) - Please accept our condolences........
As far as +P ammo, I believe you can use it safely in that gun, but there's plenty of other effective SD/HD ammo out there today, that's been developed since +P was introduced to raise the effectiveness of standard ammo.
Google "CorBon", Buffalo Bore", "Double Tap", & other "high performance .38 Special ammo makers" (Like Hornady, etc).
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