It's probably a First Degree Felony which carries 25 Years to Life. Your best bet it to try to plea bargain the case but they probably have you on film and witnesses so going to trial with the State Attorney is going to be difficult. Prepare to do some serious time especially with a minimum mandatory sentence.
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Your question is a good one but needs further information. A robbery can be a first or second degree felony depending upon the circumstances. If the weapon used was a firearm, the court is required to sentence you to a minimum mandatory prison sentence and has no discretion. There will need to be a determination if you were in "actual" possession of the firearm if in fact the weapon were a firearm, in order for the minimum mandatory to apply. If the min mans apply, plea bargaining with the State for the min man sentence is the best you can do without an amended charge if you are in "actual" possession. If the weapon is not a firearm, you total score will still require a prison sentence but there is more room for negotiations.
No person can competently tell you that pleading is a good idea without reviewing the facts. It may be correct to plea. But without knowing the facts of the case, who knows? Even when one thinks the evidence against them is overwhelming, there may be a technical defense a trained lawyer can find. In addition to a technical defense, there may just be a lack of evidence.
Find a competent lawyer to review this case. Being charged with an armed bank robbery will change your life. If you ever thought to invest resources into something important, this is it. The accused should find a criminal defense lawyer who knows what they are doing and seek their advice and guidance through this most important time in the accused person's life.