...I have been wondering that same thing!... I have a L/W 9mm. conversion barrel for my G32, Had it for about three years now and I'm only now starting to like it. For two years I tried every store bought brand and gr. weight ammo avalible. It wouldn't group worth a crap, Best group I could get out of it was football size and shape, high right at 10 yds. and they would keyhole. But with the 357 sig barrel in it I could get silver dollar size groups at 10 yds. One day while I was working with it at the indoor range I rented a G23 and slipped the 9 conversion barrel in it,,,,,,,,,,,, Same thing. Turkey platter groups. At least now I knew it was the barrel and not the gun.................. I have been reloading for about a year now and finely found what the barrel likes........................ .357 Yup .357 di. bullets, It will now shoot nice tight groups and punch clean hole's.