I agree with ARM...... a polite invite to shoot will surely get him interested.... Then you can be of help in a completely non threatening manner...... I am sure after you drill a few arrows at 30 yards in a 3" ring he will start asking plenty of questions - you can then easily look at his set up, watch him shoot and figure out just how the heck he can miss a 3 foot target at 20 yards !!

GOOD LUCK !!!