[T]he South Burlington lawmaker who just days ago proposed a dramatic amendment to gun legislation being debated in the House, on Friday backed away from two keys provisions of the measure.

Rep. Martin LaLonde, a Democrat, said he would withdraw from his amendment a proposed ban on assault-style firearms and the establishment of a 10-day waiting period for all gun sales.

The move comes a day after gun-rights advocates, in testimony at the Statehouse, slammed both initiatives as well as several others that are still up for debate.

The lawmaker said that in making his proposals he had hoped to gather information and generate discussion. He said he thought he had accomplished that with his proposed assault-style weapons ban, which by Friday proved too difficult a lift.

“I believe I will be able to go back and talk to those constituents and explain that we did look at this very carefully and we couldn’t figure out how to effectively accomplish what people are asking for,” LaLonde said. “I really worked hard how to effectively have that.”

His proposal had called for exempting firearms legally owned before the legislation would go into effect on July 1, 2018.

LaLonde said he also would be withdrawing the 10-day waiting period, following a background check, for the transfer of a firearm.

However, he said he is not yet dropping his proposed ban on high-capacity magazines, defined in his amendment as those capable of holding more than 10 rounds of ammunition.

“High-capacity magazines can lead to incidents that have high lethality,” he said. “That’s why that one is still on the table. There are still things we still need to understand about it.”

LaLonde had proposed his sweeping amendment to S.55, a bill passed last month by the Senate that expands background checks to include private firearms purchases, and increases the minimum age to buy a firearm to 21 in Vermont.

LaLonde is also proceeding with another provision contained his amendment to the bill that requires the locked storage of firearms.

The House Judiciary Committee has been taking testimony all week on S.55 and LaLonde’s amendment.

The panel took no formal action Friday, but LaLonde, who serves on the committee, told his colleagues that he would no longer be pushing for some parts of his amendment, including the proposed ban of assault-style firearms.

A big part of the problem, the South Burlington legislator said in an interview outside the committee meeting room Friday afternoon, was trying to define an assault-style firearm.

“The definition that we’ve been working with is both overly broad, that it’s going to ban more weapons that really shouldn’t be banned, and it’s too narrow, there will be ways around it so that weapons that have the high lethality and can be misused escape,” he said.

“That’s why that one has been taken off the table,” LaLonde added. “I really worked hard to effectively have that.”

Rep. Maxine Grad, D-Moretown, House Judiciary Committee chair, said during the panel’s session Friday afternoon that she hoped to keep the version of S.55 under consideration by the House panel, as close as possible to the version passed by the Senate.

The committee is expected to continue its work on the legislation starting on Tuesday next week, with a vote on Wednesday at the latest, Grad said. The measure is then expected to hit the House floor for debate Thursday or Friday.

Committee members said on Friday afternoon that there are some proposed changes to S.55 they will continue to explore next week, including exceptions regarding the age limit for purchasing firearms.

Gov. Phil Scott has voiced support for raising the age to purchase a firearm in Vermont to 21, with possible exceptions being made for members of the military and law enforcement as well as those who have completed a firearms class.

The bill that passed the Senate exempted military and law enforcement provided the firearms being purchased related to their duties.

The legislation approved in the Senate did not make an exception for those who completed a firearms class. The House panel on Friday agreed to continue discussing the exception next week.

Gun-rights advocates testified before the committee earlier in the week, They argued against imposing any additional restrictions on gun ownership, and questioned the proposed definitions of assault-style firearms in LaLonde’s amendment.

LaLonde did not list models that would be banned as assault-style firearms.

The legislation instead listed characteristics of firearms that would be prohibited. One example was a semi-automatic shotgun that has a fixed magazine capacity in excess of seven rounds, or had other specific modifications.

LaLonde said in interview Friday that he had decided to call for the ban on assault-style firearms after hearing from constituents during the weeklong Town Meeting Day break earlier this month.

A provision of S.55 requires a federal background check for the private sale, trade, or gifting, of a firearm in the state. Exemptions would be made for members of the military members, those in law enforcement and for the transfer of firearms among immediate family members.

The House committee next week is expected to take up another LaLonde proposal, to provide immunity to any licensed dealer who performs background checks in such a transfer from any civil or criminal liability.

That immunity would not apply in the event of reckless or intentional misconduct by a licensed dealer, according to the proposed amendment.