I'm not sure if you are using a scatter barrel or a rifled barrel, but if you are using a scatter barrel on your Browning, its not the best idea to use a tighter choke than the IC. The barrel is backbored and the slug will have a looser fit down the barrel, if it hits a constricted choke, it pretty much slams into it.

Alcohol, Tobacco, and Firearms... who's bringing the chips?