Have to agree that the thimble like forster slugs are not reliable. I was very impressed with the useably accuracy of both Remington and the reloads from Lee moulds, and started carrying some of them along with a few OO buck when I was out after rabbits, just in case. UNTIL at a range of between 40 and 50 meters I fired a round from a 28" full choke single barrel into the shoulder of a pig that had bolted from wallowing in a dam. I knew he would hit a fence and need to turn, so I settled in and waited for the shot. Pig was on his second step after doing 90 degree turn, slow, clear, side on target. At the shot I heard the slug thump home and saw him dropp sideways, looked down as I reloaded, and when I looked back he was up and off. I followed him 120 yards into scrub without getting a second shot and lost him, so went back to where I hit him to find blood trail. No blood, but what I did find was the slug, flattened at a sideways angle, laying on top of the baked clay, with clay and hair matted into it. Obviously at that range, just short of 50 meters, the penetration was zero. Although I could not get a clear second shot there was no sign of serious injury like broken bones in the way the pig moved.
I became less inclined to follow pig sign into dense blackberries with just the single barrel and slugs after that.