It seems like I read something about that too but cannot recall for certain when and where. You might flip through past articles of Trapshooting USA in the reloading section. All but the current issue of the magazine can be viewed online. The website address is above. I subscribe to Trapshooting USA and it's one fine magazine.
The effect may be more on pressure than it would be on velocity. Some of the data I remember seeing had some velocity change, but the difference in pressure was more dramatic. As long as there is enough of a crimp to allow for a good "burn", deeper crimps may not increase velocity as much as pressure. Some of this may vary depending on which powder and other components you would be loading.