With the speed bead, you mount the gun as you always do and there is the red dot. With a picatinny rail, you will have to raise your head to see the dot. Not a big deal unless your battery dies - in which case you are just guessing. The rail does provide options for a scope and not a red dot - so there's that.
But for a red dot, speed bead in my opinion. Have one on my Xtrema-2, but have a rail o my SP-10 - but only because they don't make a speed bead (can you hear me Burris>>??
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Ducks