How much time do you spend in jail for possession of a stolen firearm?

i would probally say about 4 or 5 years

In every jurisdiction of which I am aware, "brass knuckles" come under the category of a "prohibited weapon." You would have to check the the statutes to determine the penalty for your particular...

about up to 3 to 4 years

This question cannot be answered from the information given. Additionally there are many factors that are considered at sentencing that cannot be evaluated on line.