Vermont lawmakers are on the cusp of adopting major changes to state gun laws. The House seeks final approval Tuesday. But that won't be enough to get the bill over the finish line.

The Senate passed the bill with provisions to raise the legal purchasing age to 21 and expand background checks to private sales. Friday, the House gave preliminary approval to added bans on magazines holding more than 10 rounds and bump stocks, which allows semi-automatic guns to fire more rapidly. It's unclear if the Senate will agree with those changes.

Senate President Pro Tem Tim Ashe tells WCAX News it's too early to know if the Senate will sign on to the House changes. He says the Senate will carefully review them and take testimony this week. The biggest change-- banning magazines holding more than 10 rounds. It's a House priority.

"We feel that limiting magazine capacity is important," said Rep. Maxine Grad, D-Moretown.

Chris Bradley of the Vermont Federation of Sportsmen's Clubs has grave concerns with the magazine limit. He says he's counting on Republican Gov. Phil Scott to reject it because it will harm as many as 60 Vermont companies, like Century International Arms in Georgia and Atlas Gunworks in Ferrisburgh.

"We are fairly comfortable that the governor is not going to allow for a ban that negatively impacts the economy of Vermont," Bradley said.

House Judiciary Chair Maxine Grad says lawmakers are looking to protect those companies.

"Some of my colleagues have technical amendments to make sure that we're not accidently impacting, for instance, Vermont manufacturers," Grad said.

Some gun rights advocates are already preparing a legal strategy to undermine the potential new law.

"We already have lawyers preparing to challenge it in court," said Ed Cutler, the president of Gun Owners of Vermont.

If the House gives the bill final approval Tuesday, the Senate will have to either concur or seek a conference committee to iron out the differences.

This week's action comes on the heels of Saturday's March for our Lives rally at the Statehouse, which drew at least 2,000 people.

Bradley says the March included lots of students who he says may have been coached by adults to advance a political agenda.

"Using kids as a weapon is really inappropriate to this sort of discussion," Bradley said.

Grad says the House has worked to create sensible policies while preserving Vermont traditions. "I think the sections of the bill all take into fact, how do we balance public safety and prevent gun violence and deaths with Vermont traditions?"

The governor says he supports the bill. Ever since investigators uncovered the alleged plot to shoot up Fair Haven Union High School the governor has said everything is on the table.