antimony?

I have a Charter Arms 44 Bulldog five shot pistol.  It is one of the real old ones where when they swagged the barrel in they inadvertently narrowed the throat of the barrel.  This creates the worst possible conditions I can imagine for leading to occur. 

When I started shooting the bulldog I would get about one to two rounds out of ten that would tumble.  It still shot quite well, although anything near a warm load was rather recoil positive.  One day I decided to turn the gun into a real self defense stopper, and cast a bunch of 44 bullets in pure lead, they came out weighing about (memory) 275 gr.  I loaded these in front of 7.5 gr. Unique.  I was pleasantly surprised at the lack of recoil when I shot them.  They were very pleasant to shoot and grouped nicely.  I had no trouble staying in the high 90's for ten shots slow fire at 25yds, as an added benefit bullets no longer tumbled.  They did lead the barrel though.  In fact that barrel is still leaded.  It made to difference as far as accuracy was concerned, so I just never bothered to clean it out. 

If I ever do clean it down to steel again I will fire lap the throat of that barrel so I can use other bullets and have decent accuracy with them as well.  By the way it took a lot more than fife rounds to lead the barrel up.  A normal shooting session with the pistol was at least fifty rounds, with the accuracy never varying appreciably from first cylinder to the last.