Maybe I should state that I have worked in corrections now for almost 8 years, currently a Correctional Sergeant in my home state of AZ, and I have worked on Death Row, sex offender yards, general population yards, and max custody lockdown. I have seen inmates who I would not trust with a staple, (straightened staple, rolled up tube of paper, a bit of mattress fluff, a piece of tape, and some concrete to sharpen the staple on, and you have a blowgun. They dip the needle sharp end into a cocktail of urine, feces, semen, blood, and spit, and hope to hit exposed skin.), and I have also known inmates I would have absolutely no issue of them being behind me with a loaded gun. Admittedly THAT number is VERY small, (2), but they are out there.
I do not believe in life sentances, as they serve no purpose but to allow the individual time to plan to escape. I have known inmates who escaped on life sentances, and killed again. If a crime is so heinous to require them to be removed from society for life, then end it, as prison is either punishment, or rehabilitation, and life sentances allow for niether. You do not punish without the purpose of correcting the persons behavior, or it is torture, either physical or mental. If there is no hope of correcting thier behavior or rehabilitating them a life sentance merely gives them time to escape, and costs the taxpayers large amounts of money, running about $21k a year average to house 1 inmate.
Longest sentance should be 25 years, in my humble opinion, then let them out. As for firearms in thier hands, I did an informal survey, and every inmate I talked to said they could have a gun in thier hand the day they were released, before they were out of view of Traffic Control. I don't doubt them one bit. As it is, our prisons are pretty tame. The Mexican National inmates we get, (over 6000 right now), LOVE it here, vacation time with three hots and a cot, medical, dental, freeclothes, etc.