Former federal prosecutor David Weinstein explains the sentencing process in Florida:

In Florida, in cases where the death penalty is not an option, sentencing is within the sole discretion of the judge. The jury does not decide on the punishment.

In this case the State has alleged that, because a firearm was possessed and/or discharged during the commission of the crime of Second Degree murder, the penalty for the crime of conviction (including any lesser included offenses) should be enhanced according to the system set forth in Florida Statutes Section 775.087.

 Florida Statutes Section 775.087 has two separate enhancement sections.  These two subsections operate independently of each other.

READ | Sample of a verdict form similar to the ones jurors will fill out 

In subsection 1, the classification (degree) of the felony is upgraded one level.  This means that a felony of the first degree becomes a life felony.  A felony of the second degree becomes a first degree felony.  A felony of the third degree becomes a second degree felony.

The classification (degree) of the felony determines what the maximum penalty is for the offense of conviction.  A life penalty is punishable by a term of years of imprisonment up to life.  A first degree felony is punishable by a term of imprisonment of up to 30 years.  A second degree felony is punishable by a term of imprisonment of up to 15 years

Second Degree murder is a first degree felony.

Manslaughter is a second degree felony.

Aggravated Assault is a third degree felony.

Therefore:

If a defendant is convicted of the crime of Second Degree murder with a firearm, the classification of that crime is increased from a first degree felony to a life felony, punishable by a term of years of imprisonment up to life. 

If a defendant is convicted of the crime of Manslaughter with a firearm, the classification of that crime is increased from a second degree felony to a first degree felony, punishable by a term of years of imprisonment of up to 30 years.

If a defendant is convicted of the crime of Aggravated Assault with a firearm, the classification of that crime is increased from a third degree felony to a second degree felony punishable by a term of years of imprisonment of up to 15 years.

This enhancement only affects the maximum penalty that can be imposed and does not dictate any minimum penalties.

The second subsection of Florida Statutes Section 775.087 sets forth certain minimum mandatory sentences for specific enumerated offenses.  Any degree of murder and aggravated assault are specific enumerated offenses listed in that subsection.  Manslaughter is not a specific enumerated offense listed in that subsection.

 

Therefore, even if a defendant is convicted of manslaughter with a firearm, there is no minimum mandatory sentence applicable.

However, if a defendant is convicted of Second Degree Murder with a firearm, the following minimum mandatory sentences apply:

If the firearm is possessed, the minimum mandatory sentence is 10 years,

If the firearm is discharged, the minimum mandatory sentence is 20 years, and

If the firearm is discharged and death or great bodily harm has occurred, the minimum mandatory sentence is 25 years.

 

Likewise, if a defendant is convicted of Aggravated Assault with a firearm, the following minimum mandatory sentences apply:

If the firearm is possessed, the minimum mandatory sentence is 3 years,