Do not listen to the naysayers who disparage the magazine disconnect. More than a few lawmen are drawing breath today because of that feature.I have yet to see a documented incident of someone dying because of an inability to fire one shot without a magazine inserted.

A majority of civilian gun owners will not need to do more than present the weapon to prevent criminal attack. Should a live shooting follow it is unlikely the bad guy and any accomplices will hang around long enough to require a reload after 15 or more rounds are expended.

In fact semi-automatic pistols do not work well without a magazine in place. Shooting one that way is a good technique to generate a stovepipe malfunction, as there is nothing but air beneath the spent case during the ejection cycle.One must then clear the malfunction before reloading.

Insofar as adding features is concerned, it is wiser to either select the pistol on has in mind directly or seek a different model. I will not disparage the M&P lineup in the least, but in this instance it may be a better move to purchase a Ruger SR9 or SR40 which comes equipped with a magazine disconnect & external safety from the factory or -my personal recommendation-a used 3rd Generation S&W with the same feature.

3rd generation S&W pistols can be had in any combination of size, caliber, trigger action, and are retailing now for decent prices.A 5946 DAO generally runs under $500 shipped on gunbroker at this time, and has a Double action only trigger system in addition to a magazine disconnect.A 5906 or 5904 would work also in the role of a traditional DA first pull with an external safety.