Got a Jarvis barrel in the mail today. A little fitting and ran out to test it. It ran with everything I shot in it. Did not change the factory recoil spring, empties fell three to four steps away. I have several five gallon buckets of 40 brass so I’ll never pick up a 40 empty. I only have 10 mm magazines so far but it sure ran well today. Made some hits on pieces of clay targets at twenty yards and further. Can’t wait to put it on paper