My sp10 dials in at. .938 on the outside with a caliper
These types of procedures are best tasked to gunsmiths who specialize in this particular field
Get some quotes, and factor in the shipping rates and the purchase of a new choke tube and you will have to determine if it is worth it to choke the gun.. .or.... sell the gun on gunbroker and pick yourself up a used one with threads and often times a good aftermarket choke in it- occasionally you can get one for $250