The fired casing is State specific. I have never gotten an envelope with a fired case with any gun, any manufacturer, pistol or rifle.
I live in the wonderful state of Illinois.:no
The best way to date your S&W is to call them. Any CS agent will give you the build date from the serial number, you don't have to pay for an entire history especially on any M&P. I found this to be true with other manufacturers, some will tell you when it was built, left their plant and what distributor it went to.
Talking to S&W there is no rhyme or reason as to serial numbers and build dates. Someone in a suit decides they are going to make a run of 10,000 guns. They are going to make $100 off of each so 1 million dollars off of that production run. He puts people on it and they make sure they have all the parts they need to make 10,000. They do it and maybe the one thing they don't have is 10,000 cases. That's why some people get a black case, blue case or cardboard box.
As for the $100 profit on each, that is pretty correct give or take, the markup follows the chain. If they can dump 10,000 to a single distributor then they made a million bucks net, not bad for a day or two of production. The distributor marks them up a bunch, they go to gun shops that mark them up and by the time they get to you you are at MSRP. Basically how do think that Sportsman's Outdoor Superstore is selling the M&P40 M2.0 Compact 40 S&W Pistol with 3.6 Inch Barrel for $299.99 but the MSRP is $569?
Before I joined this forum I browsed this exact thread. I have plastic cases, cardboard boxes and polymer guns going back to a original Sigma. I decided to call S&W because I was having a hard time finding a Sigma extractor that was broken. A CS agent gave me the build date on every gun I have, including a 686 plus revolver and a M&P rifle. He also sent me a FedEx label, S&W fixed the Sigma and sent me a couple of extractors back with the fixed gun.
I am not going to post any serial numbers because while this thread is fun, you are not going to figure out a "born" date on your own. If you have the fired case you are going to be pretty close.