Hi I'm having problems with my mp40. It seems to shoot low and to the left at times. Not sure if it's me or the gun. My two previous 911 shot low and to the left. But I do well with my ruger gp100. I read where smith& Wesson is changing the barrels on the m&p 9 ' s to get them to shoot diffrent bullet weights better. I'm debating getting adjustable sights or trading it in on a ruger sr40 not sure what to do.