New AR-15 questions

A few days ago a purchased an AR-15 from my local gunshop. I took it out shooting and put about 30 rounds through it. It shoots wonderfully and is alof of fun except for one little problem that it gave me.

When it gets to the second from the last round in the magazine the bolt catch keeps the mag from raising the round high enough to be chambered. I took the gun apart expecting the remedy to be a stronger mag spring, but while apart I tried to move the bolt catch and it would not budge. It feels as though it is hitting against something metal.

Suggestions???

Try some penetrating oil on the bolt catch pivot & see if you can get the bolt catch freed up by rocking it back & forth on its pivot.

You could just use clp, or if you want to get fancy, Kroil.