I said "Drawing not photo" because a specification drawing shows only dimensions which are specified. SAAMI does not specify an extraction groove ahead of the rim of any revolver cartridge. Whether or not you like it that is the current specification for .38 S&W cartridge.
The bore of my .38 S&W mikes .361" groove diameter as nearly as I can measure a 5 groove slug. When I start to reload I will first try .358" bullets because I already have a bunch of them. If I feel the need for .361" bullets I can get them here:
ttps://www.grafs.com/retail/catalog/product/productId/21168
Or here:
.361" 145 Grain Round Nose Hand Cast Soft Lead Bullet 20-1 Alloy SPG Lube Bullet Box of 50 - Buffalo Arms
Or I can get the .360" bullets Magtech currently produces for their factory loads from here:
Magtech Bullets 38 S&W (360 Diameter) 146 Grain Lead - MPN: BU38SWA
Ain't the internet a wonderful thing?