I guess with all the contributions to this topic the crux of the matter has become lost. Is it to have a multi-caliber pistol for shooting more readily available ammunition, or is it because the OP can't find ammunition for his Model 52? I have never been a fan of multi-cal conversions as more often than not, one or all of the conversions suffer in some form. They are either inaccurate or unreliable.
If the OP REALLY wants to correct his inability to find .38 wadcutter ammunition for his Model 52 than he should put his big boy pants on and get into reloading. There is no other caliber that has more information on it for reloading than the .38 Special. In fact having a desire to reload for my Model 52 is what got me into reloading and into a deep rabbit hole. Reloading is not only fun and rewarding, but YOU can custom tailor your loads to what YOU want, not what the ammunition companies sell. I recall completing my first .38 wadcutter on a single stage press. I looked at that round and thought to myself, "Well you cost me a lot of money for one cartridge, you better work good." It did and I have far expanded my reloading infrastructure.
Certainly setting up for reloading isn't cheap, but you can save a ton of money on used equipment. I simply can't imagine shooting as much as I do without having the ability and desire to save money by reloading. This is almost always a win-win for me as my reloaded cartridges perform just as good if not better than store bought ammunition. However a word of caution should be given. Start out by the book(s), don't go off on a tangent thinking you know more than the loading manuals. Buy a GOOD chronograph and use it! Only a chronograph will give you the proof in the pudding you are looking for.
You may never feel the need to reload for a slew of calibers, but I have the equipment necessary to load for every firearm I own except .22's. It is extremely comforting to know I can shoot whatever I have, when I want to, regardless of what's on the store shelves. Now if only I could reload .22's that perform like Tennex or Center-X I would be completely self sufficient. Go for the gusto Mr. OP, give reloading for your Model 52 a try. You might be surprised at the results.
Rick H.