Brian Blanco / Reuters file Instructor Mike Magowan, right, shows public school teachers the proper way to grip a pistol during a firearms training class at the Veritas Training Academy in Sarasota, Fla., in January.

School districts nationwide have scrambled this year to implement security measures they hope will help prevent tragedies like the Sandy Hook school massacre, but many have been stymied by a lack of state and federal resources, experts say.

“After Newtown, school security was pushed to the front of the agenda for many, many schools and a number of them responded very quickly, largely due to the mass public attention to the issue,” said Ken Trump, president of National School Safety and Security Services, a Cleveland-based consulting firm.

The issue of school safety resurfaced again last week after 20-year-old Michael Brandon Hill slipped into a Decatur, Ga., elementary school on Tuesday armed with an AK-47 type assault rifle and nearly 500 rounds of ammunition. No one was hurt in the incident.

In recent months, districts across the country have moved to hire police officers, or “school resource officers,” in schools, as they have in Atlanta, Gurnee, Ill., and Steuben County, N.Y. Others are installing new security equipment, such as security cameras, or the new panic buttons in Marietta, Ga., schools. Some are fortifying front entrances or limiting access to school buildings, as they are in Plano, Texas, with new secure reception areas with buzzers.

More districts are also conducting “active shooter drills,” in which law enforcement and school staff simulate responding to a gunman on campus, in numbers not seen since immediately after the Columbine High School shooting in 1999, Trump said.

But some experts complain that localities aren’t receiving enough state and federal help to implement safety programs.

Though more than 450 school safety bills were proposed in state legislatures in the aftermath of the Newtown, Conn., shooting, which left 26 dead, 162 have failed and 310 were pending by late May, according to an analysis done by Education Week.

Bills that did become law have mostly targeted funding for school resource officers, such as those in Arkansas, Missouri, Pennsylvania, Arizona, Virginia and Indiana. Other new laws have focused on making upgrades to buildings and requiring active shooter drills. Still others, in states such as Alabama, Arkansas, Kansas, South Dakota, Tennessee and Texas, have authorized some K-12 school staff to carry firearms, according to the National Conference of State Legislatures.

Maryland and Connecticut have pegged funds -- $25 million and up to $15 million, respectively – for additional school safety measures.

But the bulk of recent school security efforts are being made at the local level, since federal funding for many programs introduced after Columbine have either expired or been cut, Trump said. “We lost all of the school emergency planning grants, the funding for school resource officers, the funding for security equipment,” he said, adding that, after Newtown, “we didn’t see any quick, new programs and resources” at the federal level.

Current federal spending cuts, known as sequestration, are only making matters worse, experts say. According to Dan Domenech, executive director of The School Superintendents Association, sequestration means a 5 percent cut in funding this school year for all schools that receive federal funds. “It’s like adding insult to injury," he said.

Curtis Lavarello, executive director of the School Safety Advocacy Council, agreed. "We have truly asked our schools to do a whole lot more with a whole lot less,” he said.

Despite federal budget cuts, one agency is re-focusing efforts on school safety. A Justice Department program known as COPS, which helped law enforcement agencies hire school resource officers, ended in 2005. In response to the Sandy Hook shooting, a similar version of the COPS’ program will this year give preference to agencies intending to employ school-based officers, said Corey Ray, a department spokesman. Some $150 million is available to fund the effort, and 771 agencies have applied for a total of 1,465 school resource officers nationwide.

Still, Domenech said not enough is being done. He denounced the failure of Congress earlier this year to pass gun control legislation that had included $150 million for school resource officers, safety equipment and the development of emergency management plans. He said his association has encouraged its members to conduct audits of their emergency management plans and make the best use of their resources.

“You come to the point where you realize that federal support has become a dream rather than a reality,” he said. “The only thing you can do is to train your staff to respond accordingly because you’re not going to get the money for the school resource officers, you’re not going to get the money for the surveillance equipment and all of the other safety things that you want.”

Despite the peaceful end to the Georgia incident on Tuesday, it could have easily turned deadly, Domenech said. “I think we’re just playing with fire here,” he said. “And it’s only a matter of time before we see another tragedy and we’ll still be sitting there saying, ‘When is our government going to act?’”

Watch more on this story tonight, August 25, on NBC Nightly News with Brian Williams at 6:30 p.m.