Last week I took my new G19.4 to the range for the first time. I experienced multiple failures in the first 60 rounds with Federal 115. Then, I focused on firming up my grip, wrist and elbow and shot the next 105 rounds without failures. This week, with a renewed focus on my grip and purchasing some 124 grain ammo, I was hoping to have zero issues. I brought 3 50 round boxes of Blazer 124 and 1 box of Aguila 147. The first 60 rounds of Blazer 124 were perfect. I also shot one mag of my carry ammo, Federal 124 HST. And after 75 + rounds, I experienced a failure to feed properly. Cleared it and went back to shooting and shortly thereafter, experienced another failure to feed. This was with the Blazer 124. I called over the range officer, showed him the problem and asked him to inspect and fire the gun. He said the pistol looked fine but could use some oil. I had cleaned and lightly oiled it last week prior to the first range trip, but not since then. He added some oil and fired four rounds without issue. He said he thought the gun was fine and to give it at least another 300 or more rounds since it was a new gun. He then watched me shoot for a while. I shot a magazine without issue, and then shot with my right (dominant) hand and had no problems. I then switched to my left hand, something I've never tried before. I probably shot 10 times left handed and did experience one more failure. However, I wasn't controlling the weapon very well and getting pretty heavy recoil. The Range Officer said that my hand was low on the grip and getting one failure while shooting that way was not a big deal. I shot the remainder of the Blazer 124 without failure, and experienced no failures with the Aquila 147. My feeling is that I got overly comfortable today after those first 75 rounds and lost the focus on my grip and increased my focus on the target. As a result, I think I reverted to some limp wristing and had those two initial failures.