I guess if we want this thread to be of any value to others I should explain what I learned so far. Or should I say, I think I learned so far. First off, I am not a gunsmith. Removing the roll stamp was very scary for me. I knew that I could ruin this shotgun forever. I purchased Nicholson medium bastard file. It had lines in a single direction and I learned that it didn't remove a lot of material in a single pass. I used common blackboard chalk to prevent metal chips from blinding the file surface. One thing I noticed right off the bat was how 'un-flat' the side of the receiver was to begin with. Also, the roll stamp was deeper at both the beginning and the end of the design. That meant that these were the last piece of the design to be removed. And that is where inexperience played a role in the final product on the second side.
I don’t know if this is correct but I found I could remove material more evenly if I cross filed where I could. It also helped me see what needed to be filed. That means filing in one direction for a little bit and then filing 90 degrees from that for a little bit. 90 degrees wasn’t’ always possible due to the fence (recoil shields) so I got as close as I could to 90 degrees. I used my thumb to protect the fence and I have the raw marks on my thumb to prove it. I worked slow on the first side and I learned to clean the work after filing as this allowed me to see what was left better. How much pressure to use on the file as well as using even pressure so the file was cutting on the entire flat surface was also a learning experience. I spent several hours removing file marks from either too much pressure or uneven pressure on the file. Getting those last two spots where the roll stamp was the deepest seemed to take forever with the file. I did try to use 50 grit sandpaper to remove those last little bits but that didn’t work real well until they were very shallow. Once the file work was done, or so I thought, I began with 50 grit sand paper to remove the file lines and moved up in grit. Again I learned after a bit of trial and error I had to clean after every step up in grit or I would miss gouges/scratches and would eventually have to go back down several grits to remove them. I ended up using magic marker over the entire surface to make sure I hit every square inch of surface with each grit of sand paper. The marker didn’t last long on the surface but it helped me on the initial pass and if I saw places that needed more work with that grit I was able to focus on those areas knowing the entire surface had been touched by that grit. I found a very small sanding pad that was just slightly larger than the widest part of the receiver that seemed to work really well. I did try using the sandpaper wrapped around the file, but my file was pretty big and I was afraid of the sandpaper slipping and gouging with the file.
The second side went much quicker. Not because I was comfortable with the process but because I learned a lot on the first side. Filing progressed well but I again was left with the two spots at the beginning and end of the roll stamp that were deeper and just seemed to take forever to remove with the file. The lesson learned here was that you can’t focus on one spot with a file. And even if the one spot is on the left side of the file you can’t put more pressure on the left side of the file to ‘get it quicker’. The last spot I had to remove was in a position where I couldn’t get 90 degrees to cross file and I thought I could file out that last little bit in one direction. I focused on the last spot and must have put too much pressure on that side of the file and ended up with a shallow groove for a ¼” above the spot extending to the water table. It wasn’t but a couple of thousandths but I could see it. Because this ‘shallow groove’ at the water table was close to the fence on that side I was unwilling to remove the material below the fence to flatten the groove for fear of weakening the strength of the shotgun. In the end I polished the shallow groove to the same 600 grit finish as the rest of the receiver and it remains. I didn’t want to aggravate a mistake by making another mistake. I’m new and if this is the worst error on my first try, I figure I’ll just have to live with it.
I hope people with experience will chime in on what I think I know and clarify what maybe I should have done.