If that "muzzle looking choke" is a PowerPac choke, then be aware that some people advise the use of fibre wad only; the PowerPac chokes have a gap between the muzzle and the start of the choke. The theory is that the petals of a plaswad could open up into this gap.
Being in the UK, this isn't an issue for me since we mainly use fibre wad, anyway.
Apololgies for the lousy photo but, for what it's worth, here is my M20 (with PowerPac choke):
Regards,
Mark.