I am trying to remember, offhand, if the bottom plate rivets from a Black Bear kit are long enough. I have to check, but I think they are. I have done this and I did use an existing rivet, not plain rod. Assuming we are talking about an assembled gun, you are going to need to use a bucking bar just like doing the bottom plate rivets. You have the same, 60 degree countersinks inside the left side plate where the rivets go. If you do it carefully, you should not have to do any clean up inside, or not much. Just smash the buggers flat on the outside, like any flush rivet job, and dress it down.
I have been using the Allegheny Arsenal solution and am very happy with it. It is very forgiving stuff. I never have to worry about the balance or anything. If it seems to be slowing down, (few bubbles coming up from the part immersed) we just throw in a few more ounces of solution. I screen the sediment out and keep the solution in a sealed plastic drum between batches. I clean the sediment out of the tank each time. It builds up again every batch, but you can do a lot of stuff per batch before the sediment starts getting so thick it wants to stick to everything. Color has been a pretty consistent, dark gray.
