Have seen this before.
Most common cause is an oversize improperly taper crimped round jammed partway in the chamber.
I cleared one by clamping the slide firmly in a padded vise.
Placed a rubber block at the back of the grip.
One good smack there with a dead blow hammer cleared it with no damage...
S&W does it differently.
Their Nation's Finest program offers rebates to LE and military.
Just ordered a M&P 9 Pro 5".
At Buds, with LE pricing, it was $499.
Then S&W rebates me an additional $50.
So $449 is a pretty fair cut from MSRP of $689
Well done.
I did the same last year. Had an 8- 3/8 27-2 that shot way high with any load.
Found a 3.5 barrel and did the deal.
All matched up well.
On my phone so I'll post an image later.