All solid advice. Axlerom1207 was a bit hard on the JBL's
. But, I certainly can't fault him for any of his words - I agree with everything he said.
I live in Madison, and have hunting Wisconsin lakes for almost 10 years. My first gun was a JBL custom. I learned to make it work. But, today, there are much better options for the $$. For the same price as a JBL, you can get a 55-75cm "eurogun" - the best choice for our water, in the 100-200 price range. As mentioned above, you do NOT want a gun with a slide ring (tears up panfish), and you do NOT want a gun longer than 75cm. And make sure your spear is "hawaiian or tahitian" style (flopper). These spears fly though panfish without tearing them up.
IMO, the absolute best gun for our water is a 32" midhandle gun. But, these are not for everyone. Mid handle guns are harder to aim than euros, and are usually 2-4 times the cost. Where midhandle guns shine is their maneuverability. I can literally shoot a crappie behind me with the twist of a wrist. And I frequently pick fish off while upside down on my descent.
Riffe makes a Metal Tech Mid-handle in this size, but I pass on it because I prefer a floating wood gun to sinking aluminum. But, most euroguns are positively buoyant becaus they have barrels filled wth foam. Having a floating gun is very important. Sinkers are fine for SCUBA guys, but freedivers should always opt for a floating gun whenever possible. It is easier on the wrists (aiming), and you'll be less likely to lose it.
Hammerhead - Sporasub - OMER - Aimrite... All better choices than JBL for hunting in Wisconsin. And all in the same price range.
I recommend a 55cm, unless you expect to routinely dive in water with exceptional visability (20 feet or better).
*edit - I should note that I DO think JBL's have a place in the spearfishing arsenal. They are the best gun for point-blank shots into the heads of giant fish that are hole-up in rocks or coral, that need to be pried out after the shot.