John; I'm able to answer the question myself now
Sounds kinda drastic, but I unscrewed a Luger barrel to compare the two. The extractor slot is slightly different (can post a picture if you would like to see), but the threads are identical. It fits nicely into the receiver without modification. Don't think any modification is needed in the extractor slot either. Think it makes sense that many Lugers are found with these barrels.