I just purchased a M&P360 and the trigger has rapidly degraded. I bought it brand new. I've been doing a lot of dry fire with it and after probably 200 reps the characteristic of the trigger has changed. This happened before I fired any ammo through it.

It went from a smooth and consistent pull to almost locking up at the first part of the pull. It's almost impossible to pull the trigger without pulling straight through. The cylinder is still tight and still rotates. I've experimented with pulling the hammer back enough to start rotating the cylinder and from there the DA trigger pull is smooth and fine.

Does anyone have an idea what is wrong with the gun?

I'd like to avoid sending it off if at all possible.