This is a bit of a long read, but has some useful info:
http://www.starsandstripesammo.com/e...tgun_slugs.pdf
Page 7 discusses choke sizes & slugs. If you're making your own slugs, it might be best to measure the slug diameter & compare it to the diameter of the choke and the thickness of the shot cup you're thinking of using.
I have a Lyman mold for 525 gr 12 ga. shuttlecock style & load 'em with Blue Dot in Win AA 2-3/4" hulls. Fired through my Winchester Defender, (Cylinder choke) the recoil is very noticeable.
HTH
Dave