Don't monkey with the gas cut off, leave it as is.
It may be the angle of the photo but it looks like the flash hider is bulged a little too. The splines look bent in the photo.
NM (National Match) is a generic term and you appear to have gotten a generic NM rifle. Lots of people claim to be gunsmiths, their finished products vary widely. Anyone can read the Technical Manuals and try to replicate what the US Army Marksmanship Unit builds, how close they come to perfection is based on their skill level and the amount of time they are willing to put into it.
What does the glass bedding look like in the receiver area? Is the trigger a crisp 4.5 lbs. with very little over travel? Does it have a National Match hooded rear sight? Is the operating rod marked NM on the top by the chamber? What markings are on the barrel? Does the trigger group lock up tight? Does it have a standard weight barrel? Medium weight barrel? Heavy barrel?
Did the seller state who built it? There is nothing wrong with the glued and screwed method of unitizing the gas system, the off center flash hider hole and the buggered front sight nut shows that whoever worked on it was all thumbs and had the wrong tools for the job.
I would return it to the seller if that's an option unless you're willing to send it off and have it rebuilt into a decent rifle. Arrington Accuracy is one of the few people I would recommend. Champions Choice can have it rebuilt as well.