Mr Heston, who is also president of the influential National Rifle Association (NRA) in the US, said Labour's anti-gun laws had led to an increase in gun-related crime.
Ann Pearston, who founded the Snowdrop Appeal, said the Hollywood star was "detached from reality".
And she stressed there was "no comparison" between the levels of gun-related crime in Britain and America.
She was speaking to BBC News Online Scotland after the Oscar-winner gave a speech to students at Oxford University.
Mr Heston, who is also president of the influential National Rifle Association (NRA) in the US, said Labour's anti-gun laws had led to an increase in gun-related crime.
He said the right to carry arms, enshrined in the US constitution, maintained freedom and actually saved lives.
The actor also described the UK's laws as "nothing but cultural cowardice and a subtle form of surrender to the criminals".
But Mrs Pearston responded: "The statistics about American deaths from firearm misuse speak for themselves. There is just no comparison between Britain and America."
Hand gun ban
The Snowdrop Appeal was founded to campaign for tighter gun laws after gunman Thomas Hamilton opened fire at Dunblane Primary School in 1996, killing 16 children and a teacher.
The group was disbanded in 1997 after the Labour government announced measures to ban hand guns.
"That was all we were calling for," said Mrs Pearston.
She said: "After the slaughter of 16 children and a teacher and the numerous other injuries people had after Dunblane, I think what the government did was right.
The group - which was named after the only flower in bloom on the day of the tragedy - handed over the campaigning torch to the Gun Control Network.
Mrs Pearston said the number of children killed by guns in America in the last 25 years was greater than the number of Americans who died in the Vietnam war.
"With those sort of statistics I don't know how he can be so distorted in his views, how detached from the reality on the ground," she said.
Human passion
Mr Heston also said that the UK laws were the result of an unwritten constitution which gave politicians too much power.
He told students: "I have spent my life in service to these two sacred sets of work. The gift of human passion in William Shakespeare and the gift of human freedom enshrined in the American bill of human rights."
But Mrs Pearston replied: "All I can say is that if he has spent all those years studying Shakespeare, he still doesn't understand what the playwright is saying about the frailty of human nature."
And she said his characters had a better chance of surviving a wound inflicted by a sword than one from a firearm.