LANCASTER, Pa. (AP) -- A central Pennsylvania man was charged Monday with involuntary manslaughter and other offenses for the shooting death of his 2-month-old daughter on Christmas Eve, and his lawyer said the man was devastated by the killing and plans to plead guilty. G. Scott Davis, 35, had been "messing with" a newly purchased 9 mm handgun and purposely pulled the trigger, accidentally hitting Kestyn as she laid in a nearby baby's swing in their apartment outside Lancaster, District Attorney Craig Stedman said. Davis was arraigned Monday on charges of involuntary manslaughter, endangering the welfare of a child and reckless endangerment. He was released on $300,000 unsecured bail, court officials said. Stedman said Davis was a novice with firearms, having fired handguns only twice; the prosecutor described his actions as "unbelievably irresponsible." Davis, who works in carpentry, was alone with the girl as his wife and father-in-law were out shopping for tuxedos that afternoon, preparing for a formal ceremony after being married over the summer, Stedman said. Davis had purchased the Springfield 9 mm on Dec. 7 but was not familiar with its features or basic elements of gun safety, the prosecutor said. Davis sat down on the couch and pulled the trigger, discharging one of 10 rounds in the weapon, Stedman said. The bullet hit the infant in her abdomen, causing such severe damage that Stedman said no medical treatment could have kept her alive. "There was nothing anyone could have done once he made the decision to pull the trigger," Stedman told reporters. Davis' wife and father-in-law arrived at the apartment moments later, and 911 was called. The baby was pronounced dead at a hospital. Davis' lawyer, Jeff Conrad, who also attended the news conference, said his client believes the charges are appropriate and will plead guilty as soon as logistically possible. Conrad called Davis "a good man and a hard-working man." "Who among us would want to be judged based on our worst day of life?" Conrad said. Stedman said Davis' story to investigators matched the physical evidence and that he seemed genuinely devastated by his daughter's death. By all accounts, he was a devoted father and was in a solid relationship, Stedman said. "To say he was devastated is an understatement," Stedman said. Davis has no criminal record, the prosecutor said. The charges could carry some jail time, but Stedman suggested that may not occur.