I have one Ive tried a few chokes in it, Mina has a 24"bbl. The X2 is overbored Invector plus choke.
I wouldnt use anything less than a Primos Jellyhead its a .670 anything tighter is to tight for it.
I tryed an Indian Creek .665 first, It was to tight and patterns were blown.Ive had great results with Indian Creek in other guns.
The Kicks .680 was good but they dont reccomend hevishot in there chokes. I waiting for a Rhino .670 that should be a good one.