If they are the correct diameter and weight, yep. Some 9mm guns have 355"-356" groove diameters, while most 38/357 bullets are .357" and up. The 9mm was designed around a 125 gr bullet and some shoot "heavy for caliber" 147 gr bullets in their 9mm pistols (and I've read about heavier), but I normally don't/won't. Also bullet length can come into play. Longer bullets may need to be seated deeper to allow the handload to chamber and reduced case capacity can raise chamber pressure drastically. But I have a mold that drops 125 gr RNFP bullets that I can size to .357"-.358" and use them in my 9mm, 38 Special, and 357 Magnum loads...
You need to know your guns before branching out of the "norm". Slug the barrel and measure the bullet. Determine suitable seating depth and make a few dummies and plunk test them. Always begin with starting load data...
When I think of purely .38 Special bullets for my own use, I'm looking at cast or swaged bullets, that I do not cast or swage myself. Bullets of that description can be found from about 100gr up. The bullets of that type that would be useful in the 9mm are 140gr or less, and usually fairly soft, BHN 12 or less. They work just fine in my 9's using load data for 115gr bullets for 105gr .358's, 125gr data for for .358 bullets of the same weight, and 147gr data for 140gr .358's.
If you don't have a grasp of the effects of OAL, different primers, etc. starting loads for jacketed bullets have not been a problem for me , but I do try to get as close to the OAL of the jacketed data as practical, and increase charge weight until I have reliable function. Starting loads do not cycle either of my 9's, so pressures are not likely very high.
Jacketed bullets can also work, but you can assume pressures will be greater, by who knows how much. I've tried a couple and feeding was a problem in my autos with the limited attempts I made, but they do work fine in my .357 BH Convertible 9mm cylinder.
I think the .357/.358 options are useful in a pinch, but not always practical. Of the bullets I've tried, the Hornady 140gr Cowboy bullet has worked the best, if you are unable to locate any 9mm bullets. Accuracy with the Cowboy's is quite good, and the shape is pretty much the same as any other 9mm bullet. They shoot the best in my.357 BH with the 9mm cylinder, where the idea first occurred to me. Loads with Red Dot and Unique were not a problem.
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