Builder, I was curious as to the thickness of the choke tubes I've worked with, so I dug them out, measured them, and made a picture of a couple:
Sorry that it's not a better pic, but my phone camera is not ideal for close-ups. The tube on the right is a Brileys tube they made for one of my guns. It is marked to move the pattern 5", though as I remember it moved my turkey load further than that. I measured it with calipers to be .044 on the wide side and .030 on the narrow side. That second measurement is something of a guess because it is dependent on how far I slide the caliper in; it gets thicker towards the base of the tube.
The tube on the left is a Carlson's .575 turkey choke. It measured .050 originally, but I have taken it down to .040 on the side I filed. The gun was off by 8" at 40 yds with my turkey loads, and this much filing was required to center it. I lost about 20% of the pattern density inside a 10" circle at 40 with this much filing. It was a very usable gun with this tube, but I wasn't satisfied losing 20% and I eventually set it up differently and no longer use either of these tubes.
One thing that I have found in filing is that it takes less of it to move a heavy turkey load than it does a field load. I'm not sure why that is, but it happens consistently. If you take a file to one, you will be trying to make it center one load. It probably won't center other loads that have different recoil.
