Just a week after making his first-ever cut on tour, the young American fired an eight-under-par round of 64 to grab a one-shot lead at a chilly St. Simon's Island in Georgia.
Hammer joined the Korn Ferry Tour this season after an impressive college career at the University of Texas, but has struggled in his few PGA Tour appearances to date.
A top-30 finish at last week's Houston Open, however, was the first sign he is getting to grips with the challenge of PGA Tour golf, and now he has the first-round lead to show for it.
"I needed to get that monkey off my back. To do that in my hometown event in Houston, was huge for me. I was telling my parents, but the first tee in Houston was like the most nervous I've ever been, just with the hometown crowd," he said.
"I told myself I'll never be that nervous again. I just got comfortable after that and saw myself shoot a good round on Tour and now I believe that I can do it.
"I basically just told myself that I can come back (from bogeys) and nobody plays perfect golf and that's what I was trying to do. I felt like on the PGA Tour you have to play perfect golf, but that's just not the case.
"Obviously I played almost perfect golf today, so it's easy to say that after shooting a really good round, but I think that just takes pressure off," he added.
Ben Griffin was a stroke behind after his bogey-free round of 65, followed by England's Callum Tarren, Beau Hossler and Ben Griffin in a tie for third, two shots off the lead.
Tarren said dealing with the wintery conditions wasn't easy.
"I had some huge mitts on, hand warmers, three layers. We actually had a 20-minute wait on hole 3, so all three of us said how cold it just got, but we were just standing around.
"You've just got to try to keep as warm as you possibly can and just try to get it in play," he said.