I'm still learning to use my drill press.  In the process, I buggered up a few of the holes on the front trunnion.  Nothing too serious, just "ovaled" out a few holes.  Is this a problem?  Will the rivet conform to the shape of the hole & keep things tight?  Thanks in advance for your help!

You're OK.

It was very common for the trunnion holes to be egged on the Bulgarian AK-74 kits that K-VAR had.

Why they had their demilling crew drill into the rivets to remove the cut front part of the receiver, instead of merely grinding the heads off, is a mystery to me.  If the bit is even slightly off, you're buggering the parts up.

The K-VAR AK-74 parts set I built up had considerable damage to the trunnion holes, but the rivets squashed to fill them up very well and everything's rock solid.