A buddy ask if I could help him sight in a deer rifle he had been having problems with. So my 15 year old son and I loaded up about 5 of our guns that we wanted to shoot and stopped by Wally world to pick up some ammo. We got his deer rifle lined out right quick and moved on to shooting other guns. We started shooting my sons Marlin .17 HMR and ran out of the Hornady hollow points we had been shooting so we shot some of my friends Hornady .17 HMR ballistic tips of the same grain and they hit 6" lower and a few clicks to the right at 50 yards. I was amazed at the difference. But the biggest surprise was with my S&W 3913 9mm. We sat up an empty box a 27" tv came in and with the cheap Remington ball ammo I picked up at Wal-mart it was all we could do to hit the box from 20'. No joke I thought something was bad wrong with my gun. We shot 100 rounds and hit all over the place. I had about 10 Federal hydro shoks with me and we put them in the gun and with three of us shooting it all ten rounds where in about a 2" group. Wow, I new changing ammo made some difference but I didn't have a clue it would do anything like that. I guess that's the fun thing about shooting. I'm 44 and still learning.