I did a quick calculation. Seems to agree with American Locomotive. Here is how I did it:
a 24" circle (1' radius) is 75.3982236862" in circumference (24*Pi.) Divide that by 360 for .2094395102"/deg. Divide .125 by .2094395102 gives you the answer .5968310367 deg
Edit: for fun I went back and carried out a few more decimal places.