Make sure you have a good bell on the case and not shaving through the coating during the seating process.
If you are using brand new brass, make sure there is not a sharp edge on the inside of the case mouth (try used brass).
Make sure you have a good crimp.
If you are using the Lee Factory Taper Crimp Die, try switching to a standard taper crimp die.
If you are seating and crimping in the same die, try switching to a separate seater and taper die.
Try a slower powder.
Powder Burn Rate Comparison Chart
Slug your bore, oversized bores will foul heavily and be inaccurate. (
Midway USA sells a good slugging kit.)
Article: Slugging Handgun Barrels