A.J. Wynne shoots a Heckler & Koch MP 5 short-barrel rifle with a suppressor. He spent the afternoon target practicing with a variety of high-powered weapons at a shooting range. (Michael S. Williamson/The Washington Post)

When hunters argued that Maryland Gov. Martin O’Malley’s proposed assault-weapons ban would ruin their sport, state lawmakers were not moved. When devotees of the National Rifle Association cried that it would trample on their constitutional rights, lawmakers did not blink.

But then there were the soldiers, who showed up in Annapolis by the dozens this year and quietly became one of the most influential critics of O’Malley’s gun-control plan. Veterans streaming back from Iraq and Afghanistan have argued that freedoms they fought for overseas would be violated at home.

Some also came with a different, more complicated message that has resonated with lawmakers, who are now considering significantly weakening the proposal by O’Malley (D) by exempting several military-style weapons.

The very guns the veterans used in war — the ones they sang about in boot camp, slept with, cared for, cleaned, prayed with, the guns that led them down dark alleys and through firefights — have now become something altogether different. They are instruments of catharsis more than violence, a postwar release, therapy through the crosshairs.

Since he has returned from Afghanistan, A.J. Wynne, 24, who was a corporal in the Marines, has spent countless hours shooting in the farmland north of Frederick. On a recent Sunday, he picked up his semiautomatic rifle, put down his demons and let muscle memory take over.

Breathe. Focus. Squeeze.

The weapon erupted into a violent cacophony — 30 shots in 11 seconds — and sent the crows in the treesbolting skyward.

The smile made his beard rise. He reloaded.

“It’s not yoga — it’s not graceful in any sense of the word, but I could do this all day long,” he said. “It’s just something that you go do to relax, to calm down.”

Wynne knows there are those who would argue that he is perhaps the last person who should be given unfettered access to high-powered, semiautomatic rifles that are designed to emulate the weapons he was trained to use in battle.

For months after coming home, Wynne would lunge to the ground at the sound of a weapon firing or a car backfiring. At night, he would awaken to find himself wrestling an invisible enemy, flailing and slamming the nightstand and leaving his girlfriend, Tara, cowering at the end of the bed.

The nightmares have subsided, but guns have become an ever bigger part of his life. He sells them, trains people how to shoot them, collects them, and has positioned them around his home so they are never more than a few steps away.

As the House of Delegates debates O’Malley’s bill, the veterans’ argument appears to be having an effect. After passing the Senate, the legislation is bogged down in an influential House committee, where lawmakers say they are concerned about the effect of the assault-weapons ban. Members of both parties say they are considering rolling back provisions of O’Malley’s ban, potentially leaving legal for purchase many semiautomatic rifles modeled after military ones.

Del. Kathleen M. Dumais, a Montgomery County Democrat and vice chair of the House Judiciary Committee, said veterans and competitive sportsmen were central factors in her thinking that a total ban may be inappropriate.

“We have problems with soldiers returning from combat and taking their own lives. That’s a big deal, and we need to talk about that overall in this country,” added Del. Michael A. McDermott, an Eastern Shore Republican and former member of the U.S. Army Reserve. “But banning these weapons? For some guys, that’s actually therapy. They go to the range. They enjoy shooting sports. It’s something that helps them recover and have balance in their lives. If we start taking that away, it’s only going to hurt, not help.”

That’s far from a universally accepted premise.

While he understands that many like to shoot for recreation or even relaxation, Lt. Gov. Anthony G. Brown (D), a colonel in the Army Reserve, said that doesn’t mean you need to have a weapon designed for war.

“It’s nonsense,” said Brown, the highest-ranking U.S. elected official to have served in Iraq. “The military trains us on these military-style assault weapons to perform a combat mission, and that combat mission does not exist in the communities of Maryland or anywhere in this country.”

Gun industry data suggest that recent veterans are one of the country’s fastest-growing segments of buyers of semiautomatic rifles. Gun manufacturers have increasingly marketed to them, and the NRA has focused a membership push on active-duty and recent veterans.

Wynne may be among Maryland’s most prolific purchasers of rifles that O’Malley would like to ban. Since returning from Afghanistan two years ago, Wynne has purchased seven semiautomatic rifles — a side effect, at least partly, of his day job at a gun shop in Montgomery County. He also just likes shooting them.

“I hear a lot of people say they’re willing to move rather than abide by this law,” Wynne said. “I say, ‘Why?’ — why do I have to move from the state that I grew up in — that I went over and served in Afghanistan for? Why do I have to come home to a state that denies my fundamental right?

Polls show that residents in Maryland overwhelmingly support an assault-weapons ban as well as other rules proposed by O’Malley, such as fingerprinting gun buyers.

But the plight of veterans is one lawmakers, especially in the House, have heard loudly.

Veterans were a heavy presence among more than 1,300 people who on March 1 amassed in Annapolis to testify against O’Malley’s plan. Many cited federal data to stress that their rifles are for good, not for harm: Out of 398 Maryland homicides in 2011, two were carried out with rifles.

Witness No. 74 was Adam Obest, a staff sergeant in the Maryland Army National Guard, who was last abroad working in Egypt. Seeing how quickly security deteriorated there, he said, buying a gun was his top priority upon returning to Maryland.

“I came home and bought an M4 and $1,000 worth of suits at Joseph Banks” to look for a new job, said Obest.

“I want to be able to be an asset to my community if I am needed. If there is a disaster, and the road is blocked and I can’t get to the armory, I want to be able to tell my mayor that, ‘I’ve got this. I’m here. I can help keep order.’ ”

Ryan McDonald was witness No. 684. He survived two explosions in combat outside Baghdad in 2004 and 2005 and remains in the Army reserves. He shoots an AR15-style rifle on the weekends. “In the rare case where you could be called up again,” said McDonald, 29, “it might be nice to have the skills.”

Wynne was witness No. 900. In 2010, Wynne deployed to southern Afghanistan, where he was sometimes assigned to guard the perimeter of bases.

Wynne fired only once, after a commander squawked on his radio warning that combatants were planting explosives near a path that convoys traveled to the base. He is still not sure whether he hit anyone.

“I could probably still pick the gun out of the armory by feel. It probably rested in my shoulder within a millimeter of the same spot every time.”

Kate Havard contributed to this report.