A little advice.
Shooting the BB inserted in the pellet shooting the iron plate. That BB will bounce back like a ball bearing. I did that once with shooting a .22. I had factory primed .22 cases I use for loading black powder loads, still have a couple thousand primed rimfire cases left. WHat I did was make a wax bullet with the BB and used it for basement practice with just the primed .22 cases and that shot great at 50 feet. But when I put a blk powder charge in the case and shot a plow Plow Moldboard that BB came back and hit me in the chest. I'm glad it was cold out and I had the carhartt on with heavy shirts under the bibs, it still stung.
That is one fine squirrel shooter!!