I would appreciate any thoughts on this one.

I took my S&W M&P to the range and was firing a few 135grn speer dot 38 sp. On my 2nd shot the bullet went downrange, the cylinder locked up, the trigger was all the way to the rear and the cylinder release appeared to be engaged all the forward but unable to swing out the cylinder. I don't know what resolved it but after attempting to swing out the cylinder at a certain point it just 'resolved' and I stopped firing for the day. Any thoughts would be greatly appreciated to this revolver noob.
Thanks!
As a side note this does have the apex spring kit installed.

Couple of things can cause that, you say it 'resolved'...does that mean you were able to get the cylinder open?

Obviously the spring kit is the first place to look, maybe go back to stock and shoot with the same ammo to see if the problem recurs.

Thanks for the reply. It had occurred on one previous occasion with the stock spring setup.
Yes by resolved the cylinder all of a sudden swung open and trigger moved to the forward position. Don't know exactly what movement enabled this to occur.

any general wisdom would be appreciated. I ended up going the revolver route for the 'reliability' and now confidence in this ccw is up in the air~