One of the downsides of switching from Glocks to the M&P is that you don't get to use the 33-round "Happy Sticks" anymore. That is, until now.
One of my guys knocked this together, using two M&P magazines.
I was able to get 30 rounds in there before I got tired of loading it. With some refining, we're pretty confident it can hold more. In testing, we were able to send all 30 rounds downrange with no problems.
Adding an Arredondo extended basepad could theoretically get you even more rounds. We'll test that soon enough.
If an enterprising manufacturer wants to make these, there's definitely a market! In the meantime, we're hoping to make a few more.