An inning earlier, Reynolds drove in a run with a double that sailed high over the head of Rangers right fielder Engel Beltre, who lost the baseball in the sun.
"I said after I hit that popup and he lost it, 'That's what I needed,'" said Reynolds, who leads the Brewers with 10 RBIs, but is batting .200 this spring. "Just a little confidence. I was able to get a good swing on that [grand slam], too.
"I feel like my timing is coming back and I can start barreling some balls and put some good at-bats on them. Sometimes it takes a swinging bunt, a swinging whatever -- something to boost your confidence, because it starts to eat at you, even in Spring Training. It was good to get on the board."
Gomez's homer was also his first of the spring. Seven of the outfielder's nine hits this spring have gone for extra bases.
Estrada scattered four Rangers hits, struck out five batters and walked none in the best outing by a Brewers starter this spring. Estrada has now worked 12 consecutive scoreless innings over his last three starts.
Rangers starter Martin Perez kept the Brewers off the bases until the fourth inning, but he was charged with five earned runs on five hits and a walk in five innings. He struck out three.
"I threw a lot of strikes," Perez said. "It was better than the last time. I attacked the zone a little more and was under control. My curveball was good. My changeup was good."
Perez should have been out of the fifth inning without allowing a run. But after a leadoff walk by Rickie Weeks, Khris Davis lined out to left. Brad Snyder made a strong throw to first that should have doubled off Weeks, but first baseman Ronald Guzman couldn't handle the throw.
Reynolds followed with a high fly to right that Beltre lost in the sun. It fell for a double and Weeks scored. After Martin Maldonado reached on a bunt single, Gomez delivered his homer.
After a hit batsman and an error in the ninth, Rangers prospect Ronald Guzman broke up the shutout with a three-run homer off Brewers righty Donovan Hand.
Up next: Right-hander Wily Peralta will continue his Spring Training task of honing his changeup when he takes the mound against the Mariners in Peoria, Ariz., on Wednesday. After a pair of scoreless appearances to begin his spring, Peralta has surrendered three earned runs in each of his last two outings against the Indians and D-backs. The game can be heard via an exclusive webcast on Brewers.com, with radio play-by-play man Joe Block on the call.