Delia said he has sold about 30 AR-15 military-style weapons in the past week to customers who are concerned that Congress will ban them.
An assault-style rifle was used in the slaying of 20 children aged 6 and 7, and six adult staffers at the Sandy Hook Elementary School.
"They are getting scared as far as the Obama administration banning guns," Delia explained.
With President Obama vowing to seek new restrictions on the sales of military-style rifles, purchases of those and other types of guns has been fevered. This kind of rush to buy arms that might be banned has happened in the wake of other national tragedies.
Not far from Delia's shop, the scene was the same.
"We're up about 25 percent," said an employee at Frank's Double Tap Shooting Range & Gun Shop on Blakiston Street in the Northeast. He declined to be identified.
"It's crazy. We are totally out" of automatic rifles, said Andrew Podobed, a salesman in the gun department with Cheyenne Mountain Outfitters in Robbinsville, N.J. "I've never seen it like this."
The store sold out of assault rifles two days ago, and Podobed said he did not know when they would restock.
"We can't even order them, it's so backed up," he said.
Connecticut and Congress were not the only factors, Podobed said. Some seemed motivated by the Mayan doomsday theory.
The surge in sales is nationwide. The Hyatt Gun Shop in Charlotte, N.C., reported sales of more than $1 million Wednesday. On eBay, shoppers have bid up the price of the large-capacity ammunition magazines that are a feature of such weapons.
Sales of assault weapons spiraled in the late 1980s after Congress began debate on banning them. The debate was set off by the schoolyard shooting in California of five children in 1989 by a troubled drifter with an assault rifle.
They surged again after the Columbine school shootings, when many gun owners rushed to beat what they believed would be new restrictions. The result of that congressional debate was a system of national background checks aimed at screening convicted felons, people accused of domestic violence, and certain others from owning guns.
Delia, silver-haired and bespectacled, and many other gun enthusiasts insist that the system remains riddled with loopholes, largely because it fails in many instances to report people with troubled psychiatric histories.
"It scares me sometimes," Delia salesman Terry Boarts said of the lack of knowledge about a customer's psychiatric history. "We just don't know from the background checks."
Obama has delegated the task of crafting gun-control legislation and pushing it through Congress to Vice President Biden, the primary architect of the 1994 federal assault-weapons ban. Philadelphia Police Commissioner Charles H. Ramsey is serving on an advisory committee Biden has assembled.
At a news conference in Harrisburg on Thursday, Gov. Corbett said in response to questions that gun legislation would be a federal decision. He added that legislation is "something we ought to begin the thought process on."
"This is something that is less than a week old," Corbett said. "Let us digest this. Let us see what we can do. Let us sit down and talk about it."
The problems faced by legislators after previous mass shootings illustrate the hurdles before Congress.
Adam Lanza, the troubled 20-year-old shooter in Newtown, used an assault weapon to kill his mother with a rifle registered to her before entering the elementary school.
Such weapons have a military appearance and bear little resemblance to traditional hunting and target-shooting weapons. Yet their core functionality, the ability to discharge one cartridge with each squeeze of the trigger - a feature that makes them highly lethal - is the same as in many sporting weapons used for hunting wildfowl and, in some states, deer.
The 1994 assault-weapons ban sought to reduce the lethality of these weapons by sharply restricting large-capacity magazines - which hold the large number of rounds such weapons could carry. That will likely be on the agenda as gun-control advocates seek to enact new restrictions.
Delia pointed out that there might be problems with that approach. Congress might ban large-capacity magazines, he said, but there already are vast numbers of such magazines in private hands.
"I have a box of them in my attic," Delia said.
The gun merchant said he favors "sensible" gun control that would have, at its heart, denial of weapons to individuals with unstable personalities or troubled psychiatric histories.
It's not clear whether Lanza would have been flagged by a system that focused more on psychiatric disorders. Lanza reportedly had a form of autism, and medical experts say autism is not associated with the kind of violence that took place in Connecticut.
The days after the Newtown massacre have been busy for places that sell handguns and rifles of all sorts.
Cabela's, a national retailer of hunting and outdoors equipment headquartered in Nebraska, is to guns as Tiffany & Co. is to diamonds. The phones at the Cabela's off I-78 in Hamburg, Pa., were busy Thursday evening. A message asked callers to leave their names and numbers for callbacks.
Contact Chris Mondics at 215-854-5957 or firstname.lastname@example.org.
Inquirer staff writer Bob Fernandez contributed to this article.