Ron Pinciaro, executive director of Connecticut Against Gun Violence, said his group will live with the lawmakers' decision not to ban them as other states have done. He said the leaders made their decision based on what was politically feasible.
"We have to be satisfied. There are still other things that we want, we'll be back for in later sessions," he said. "But for now, it's a good thing."
Robert Crook, executive director of the Connecticut Coalition of Sportsmen, contended the bill would not have changed what happened at Sandy Hook Elementary School, where the gunman fired off 154 shots with a Bushmaster .223-caliber rifle within five minutes. He went through six 30-round magazines, though half were not completely empty, and police said he had three other 30-round magazines in addition to one in the rifle.
"They can register magazines and do all the rest of this stuff. It isn't going to do anything," he said.
Gun owners, who've packed public hearings at the state Capitol in recent months, voicing their opposition to various gun control measures, are concerned they've been showing up "for virtually nothing" after learning about the bill, Crook said.
"Clearly we've made our point," Crook said. "But I don't know what anybody can do at this point in time."
Six relatives of Newtown victims visited the Capitol on Monday, asking lawmakers to ban existing high-capacity magazines. Some handed out cards with photographs of their slain children.
Allowing magazines that carry 10 or more bullets to remain in the hands of gun owners would leave a gaping loophole in the law, said Mark Barden, whose 7-year-old son, Daniel, was killed in the shooting.
"It doesn't prevent someone from going out of the state to purchase them and then bring them back. There's no way to track when they were purchased, so they can say, 'I had this before,'" Barden said. "So it's a big loophole."
Barden and other victims' family members who visited the statehouse earlier on Monday did not immediately respond to messages seeking their reactions to the agreement.
Jake McGuigan, a spokesman for the National Shooting Sports Foundation, which is based in Newtown, said he wouldn't comment on the proposal until he saw it in the writing, but he questioned the mechanics of a registry for magazines.
"How will they register a magazine? It seems a little weird," he said.
Associated Press writers Stephen Kalin, Stephen Singer and Michael Melia contributed to this report.