A senior policeman has accused some judges of being lenient on gun crime by overlooking mandatory five-year sentences for possession of a firearm.
Merseyside Chief Constable Bernard Hogan-Howe told the Times it was wrong for judges to ignore such sentences.
He said no-one wanted a repeat of last year's murder of Rhys Jones, 11.
The Ministry of Justice said the five-year term was "a starting point", but mitigating factors must be weighed in deciding the final sentence.
The average sentence handed down for possession of a firearm in 2005 was three years and nine months. About 40% of offenders were given the five-year minimum sentence.
A Ministry of Justice spokesman said: "The mandatory five-year term for possession of a firearm is a starting point.
"Judges must then take aggravating and mitigating factors into consideration when determining the final sentence."
He added: "Sentencing in individual cases is a matter for the courts."
In October last year a judge at Manchester Crown Court jailed Natasha Peniston for three years, rather than the mandatory five, for possession of a gun which accidentally killed her daughter Kamilah as her son Kasha played with it.
Sentencing her, Mr Justice Holland said there were exceptional circumstances to justify her not receiving the mandatory term, as she had been "prevailed upon" by a boyfriend to look after the weapon.
Natasha Peniston was sentenced to three years for firearm possession
Mr Hogan-Howe's force is still hunting the killer of Rhys, who was shot dead as he walked home from football practice in Croxteth Park last August.
Officers are understood to have held meetings with the local judiciary and members of the legal profession to discuss the effects of gun crime on the Merseyside community.
As well as the five-year minimum term for possession, he would like to see 10-year sentences for firing a weapon, Mr Hogan-Howe said.
Speaking to BBC Radio 4's Today programme, Mr Hogan-Howe said his comments were not an "attack on judges, nor a condemnation of them".
"There have been some excellent examples where the judges have handed down some very long sentences."
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He highlighted a recent Merseyside case where two men found in possession of 11 firearms were sentenced to 15 years and eight years.
He said: "That is the type of sentence that starts to be a deterrent.
"This is a plea for more consistency. The value of a gun in cash terms is very low. It can be as low as £500, possibly £1,000. If we can get into the mind that not only is it a low sum of money, but you're going to prison for 10 years or 15 years, they will listen.
The Tories claim Labour has overseen a fourfold rise in gun crime
"But we've got to get that message consistently. I'm afraid that at the moment it's inconsistent," Mr Hogan-Howe said.
Shadow home secretary David Davis said Labour had overseen "a four-fold increase in gun-related violence" while in government.
"The problem is, they are happy to pass tough laws in order to get a good headline only to simply not enforce them - allowing the situation to deteriorate at great risk to the public," said Mr Davis.
"As well as failing to enforce the law, our porous borders allow weapons to simply flow into the country while the government's failure to combat the scourge of drugs also fuels so much violent crime."
The Liberal Democrats' home affairs spokesman, Chris Huhne, said there was an "increasing gap" between what the government says about penalties and what sentences the judges hand down.
"There is an increasing disparity there - and I think we do need to make sure that we're getting across to people that this is an area where we feel very strongly that there has to be a very firm view taken by the courts."