BOSTON (AP) — Days after the mass shooting that killed 58 people and injured hundreds more at a Las Vegas music festival, Massachusetts appeared well on its way to becoming the first state since that tragedy to impose a ban on devices intended to increase the rate at which a firearm discharges.

That still may well be the case. But as often happens on Beacon Hill, procedural issues and disagreements between the House and Senate have temporarily stalled the measure and along with it an appropriations bill needed to close the books on the 2017 fiscal year, which ended June 30.

Gun rights advocates, meanwhile, are upset that lawmakers approved of the bump stock ban without first holding a public hearing. Instead, a group of Democratic senators hastily called an "informational" hearing at the Statehouse last Wednesday — after votes had already been taken in both chambers — ostensibly to offer the public a chance for input before the final language of the bill was determined.

The sparsely attended meeting lasted only 20 minutes and lawmakers were the only ones who spoke.

"Process is everything up here, and unfortunately the process has been very flawed," said Jim Wallace, executive director of the Gun Owners Action League of Massachusetts, an affiliate of the National Rifle Association.

Wallace told reporters that at this stage of the legislative process, there was no point in him testifying at the informational hearing. But he did express a preference for the narrower Senate language over the House version of the ban.

Investigators have said that Stephen Paddock, the gunman who fired on the crowd from his Las Vegas hotel room before killing himself, employed a bump stock that allows a semi-automatic weapon to mimic the more rapid fire of a fully automatic one.

The amendment approved by the House does not specifically refer to bump stocks but would allow for a prison sentence of between three and 20 years for anyone who "possesses, owns or offers for sale any device which attaches to a rifle, shotgun or firearm, except a magazine, that is designed to increase the rate of discharge ... or whoever modifies any rifle, shotgun or firearm with the intent to increase its rate of discharge."

The Senate language, by contrast, would limit the ban to bump stocks and "trigger cranks," with specific definitions provided for both.

Wallace contends the House language, if applied literally, could make a felon out of a gun owner who by cleaning a hunting rifle makes its bolt action faster or smoother.

"I think we should be careful to use language that is very specific as we did on the Senate side," said Sen. William Brownsberger, a Belmont Democrat who co-chairs the Legislature's Judiciary Committee.

Brownsberger agreed the broader House language could carry "unintended consequences," though he also acknowledged that limiting the ban specifically to bump stocks and trigger cranks could fail to account for any similar mechanisms developed in the future.

It's unclear how many such devices exist in Massachusetts, which has some of the nation's strictest gun laws and lowest firearms fatality rates.

Rep. Donald Berthiaume, a Spencer Republican, said he'd been doing shooting sports since childhood but until the Las Vegas massacre had never heard of a bump stock. Wallace, too, said he could not recall ever seeing one close up.

Complicating matters further is that both versions of the proposed ban were attached as riders to different versions of the $85 million appropriations bill. As of Friday it was unclear when or if those differences might be reconciled.