BILLERICA — Roxanne O'Connor convinced her nephew, Walker, that New Hampshire state law prohibited him from beating up his younger brother, Cole, in the back seat of her car. For 13 years, he obliged.

However, once Walker uncovered the faux law, he made sure he snuck a few brotherly jabs Cole’s way during the rides to their aunt's house.

“Those were just to keep him in check,” Walker said, joking. Now, Walker and Cole O’Connor dedicate their efforts toward punching out opposing hitters for the Billerica American Legion Post 268 baseball team.

Behind the strong pitching of the O’Connor brothers, Billerica cruised to a 17-2 regular season record and will enter the district tournament as the top seed from Zone 5.

Walker, a 19-year-old graduate of Malden Catholic, allowed just two runs in 37 innings pitched while compiling a 5-0 record. Cole, a 15-year-old sophomore at Buckingham Browne & Nichols School in Cambridge, was 4-1 in his first season with the team and played shortstop regularly when Walker pitched.

“[Walker's] been a tremendous help for three years,” coach Richard Gearin said after the team's 16-4 victory over Watertown in the last regular-season game Wednesday night.

“Cole has helped us immensely as a young kid coming up; we'll have him for two or three more years hopefully and we'll look for bigger and better things out of him.”

This season marks the first that the O’Connor brothers have played on the same team together — it has been difficult to span the four-year age difference.

“I think it’s been fun, it’s been a good time,” said Walker, who will attend West Florida University this fall. “[Cole's] a good competitor and I love playing with him.”

Cole added that his brother is “really good, so that makes it a lot easier.”

As children, the O’Connor brothers were extremely competitive — often comparing to see who had the better performance and trying to strike each other out in their backyard.

“We'd go home and ask who had the better day at the field, and our parents would both give us [a hard time] about who had the better day,” Walker added.

That said, they also became extremely supportive of each other — a characteristic that has helped them achieve their success with the Billerica Legion team.

“We played AAU in the same program and I was in the 15s [age division], and Cole was in the 13s and I would always root real hard for [Cole] and give him advice and motivation when he went down to his tournaments,” he added.

“He gave me a lot of pointers so it helped out a lot — but I show him some tips on pitches too,” Cole said, giving his older brother a playful nudge.

The inseparable bond between the 5-foot-10, 170-pound Walker and 6-foot, 170-pound Cole is a microcosm of the Post 268 team — a tight-knit group of players from eight high schools.

“We have a great group of kids, and we really blend together no matter what school we’re coming from,” Walker said. “We’re just having a really good time and we’re just rolling.”

Gearin hopes his team can keep rolling through the district playoffs, a double-elimination bracket consisting of the top four teams from Zone 5 and Zone 8, which can begin as early as Sunday.

With the sure-fire pitching of the O’Connor brothers and Belmont Hill School graduate Soren Hanson (5-0), as well as some timely hitting, Gearin believes his team is poised for a deep tournament run.

“Matt Clifford, our centerfielder, he's probably been our hottest hitter down the stretch,” Gearin said. “Hanson, Walker — they’ve all been hitting the ball and we’ve been scoring some runs when we’ve had to.

“We’re hoping we don't let down any, but we’re the number one seed and we get to face the fourth seed from Zone 8 and hopefully Walker will be pitching and we’ll get to move on.”

Gillis helps boost Nashua to the top

The Nashua Silver Knights (31-9) enterered Thursday's All-Star break with the best record in the Futures Collegiate Baseball league with a 31-9 record — 7.5 games ahead of the Martha's Vineyard Sharks.

Spearheading the Silver Knights’ success is Merrimack, N.H., native Logan Gillis, a Lawrence Academy grad who is hitting .333, the seventh-best average in the league.

Gillis, the 2011 league batting champion (.376), was named the Player of the Month for June after hitting .438 average in 19 games.

“I got off to a pretty hot start that I definitely enjoyed for the month of June,” said Gillis, who was named a league all-star. “As a team, we did great. We had five losses in June after losing our first two games at home.”

For Gillis, his soaring success in the league comes as an extension of what was a stellar junior season at Bentley after his transfer from Northeastern.

The second baseman hit .312 with 38 RBIs after a .313 campaign with 26 RBIs as a sophomore at NU.

“If you look at my numbers — they’re typically higher in the summer, and not having to worry about school and all the classroom stuff allows me to have more fun and focus on baseball,” said the 5-foot-8, 175-pound right-handed hitter.

“I think that's a big part of summer baseball, just learning how to enjoy the game and not put too much pressure on yourself and to always succeed.”

“I'm looking to carry that over into my senior year and enjoy it, because it could be the last time I play baseball.”