I had a really nice 45/410 10 inch barrel for about a year. I shot it over and over and couldn't hit a dang thing with it. I am a reloader and I tried several different loads and still got scatter out of it. At 50 yards, about one third of the rounds key-holed my targets. I finally gave up on the 45 Colt's and just played with it for a while, shooting the 410's. The 410's were quite fun but it wasn't worth keeping the barrel just to shoot a few plastic bottles etc.
When you think about it, the barrel is made to fit 3 inch shells and then when you remove the choke to fire 45 Colts, you really only have about 7 inches or less of rifling in the barrel. Aside from three inches less of rifling, add to the trouble a 1 inch jump from the face of your 45 Colt rounds to the lands and you have a good recipe for inaccuracy and tumbling bullets.
When I bought my barrel, I was really looking for a good 45 Colt barrel in which I could work up some strong and accurate loads. What I ended up with was a waste of time and money. I'd say that if you're looking for accuracy and power, buy a Ruger Blackhawk with a 7 1/2 inch barrel or a dedicated 45 Colt barrel without the 410 option for your Contender.
Maybe other shooters have had different results, but that's what I got. Personally, I don't know why T/C even sells the barrel with the 410 option. Can one legally hunt rabbits etc with a 10 inch shotgun barrel?