Good grief, I've actually got that Charger article. It's a 25'ish sized high wing cabin model that used an older .35 on it. It was designed by a Milt Boone and was published in the Jan 1960 American Modeller. I guess Ambroid picked it up as a kit after that.

The amount of dihedral isn't excessive. It's a 48 inch span with 2 1/2 inches under each tip. The fin and rudder aren't particularly large. I suspect the smaller vertical area has something to do with it being snappy. A little spirally unstable perhaps.

If any of you are interested in this old classic I could scan the magazine article I have sitting here in front of me and get it on in the next few days.