They are good. I have seen a few and usually groupings do get smaller than the stock barrel. And it will be safer with the extra chamber support. Lone wolf, barsto, and kkm are some other good ones too. Whichever you get make sure to
clean the barrel really good. That, along with the replacement barrel, will help prevent case-bulging in Glocks in regards to the .40's and 10mm's. And then you shouldn't have any problems. Rock on!
