I bought a Lone Wolf/Alpha Wolf M&P Shield .40 S&W to 9mm Conversion Barrel and dropped it right in, and it was nice. Much less snappy than shooting the Shield in .40 cal.

I put 100 rounds of Federal FMJ 115 grain rounds through it, using my .40 mags, with no problems what so ever.

I will get me some 9mm mags next, for when I do carry with the 9mm barrel though.

I bought the barrel through Optics Planet and had a very good experience with those guys.

Thanks for posting this up. I have a 40 shield and I've considered a conversion but backshelfed it. Glad to know it runs with just the barrel change though yes the 9mm mags are probably a good idea.