(Taking deep breath),OOOkay........
The marking on any choke, both fixed and changeable, indicates a mere probability. A shotguns'interior ballistics are so subject to a myriad of factors that quantum physics pales in comparison.
I could make a full choke act like an IC by changing loads, and almost vice versa.
Unfortunately, there's no way on earth that we can guarantee that choke X in bbl Y will produce Z pattern. It takes testing to find out what load, choke combination will do a particular job best.
Since we're talking about turkey hunting here,it becomes a bit easier. Set up your turkey gun with a fairly tight tube, say from Improved Modified to Extra Full. Start patterning with a turkey target, and use those 10 packs to keep the cost down. Find out which load CONSISTENTLY places lots of pellets in the head/neck area, then buy more of them. And keep your shots inside a reasonable distance. If you can call/decoy them into 30 yards(or whatever) regularly, pattern at that distance.
If NO load shows good performance, go to another tube.You WILL find a great load for YOUR shotgun with a bit of work.
A note, oft times a forcing cone job will do more good than an aftermarket custom choke. Cheaper also.