The 40-second advertisement, which was only shown in cinemas for the first time yesterday, features the voice of the former James Bond actor Sean Connery.
It was unveiled last month and is designed to win support for an extension to the Government ban on handguns to include .22 pistols.
The campaign is being run by the Snowdrop Petition which was set up after Thomas Hamilton gunned down 16 children and their teacher at a primary school in Dunblane in March 1996.
The advert shows a man loading a .22-calibre handgun and firing at a human shaped target which is devastated by the shots.
The London ad agency which produced the advertisement and is distributing it free of charge has hit back at critical pro-shooting campaigners.
Barry Delaney of Delaney Fletcher Bozell said: "The gun lobby started having a go at this before they had even seen it."
He rejected the claim by Phil Thomson of Shooting Times that a .22 handgun could not pose a threat or kill people.
"It is a very feeble argument and an example of their desperation," he said.
Mr Thomson said that a ban on .22 handguns was no guarantee against another tragedy such as Dunblane.
He said: "If a complete ban on guns would guarantee that this (Dunblane) would never happen again, you wouldn't find a gun owner in the country who would object. But in reality it would not work."
Gun enthusiasts are slating the commercial as a misrepresentation of the truth, and are even more incensed by the fact that Connery is involved, claiming he made his name playing the gun-toting James Bond.
However, Ann Pearston of Snowdrop, defended the former Bond star, saying he had made the James Bond films 25 years ago.
"He is a voice in Hollywood as is Dustin Hoffman who has spoken out against violence in films," said Mrs Pearston.
"That is good because we are not going to be able to do that and be heard."
A spokesman for the Advertising Standards Authority said no action would be taken over the advert until it had received complaints from people who had actually seen it.