Nice rifle. Something sexy about iron & wood!
Looks to be around a 2 1/2 MOA group, which isn't bad for irons (assuming ball ammo). With quality ammo you might shrink that down a bit. The irons on an M1/M1A are great and you can easily make man-sized hits to 600 with them, with a little practice.
While some folks prefer optics on their M1A, bear in mind you might need some kind of cheek/stock riser in order to get proper cheek weld. Those mount set the optics fairly high above the bore.
Keep at it!