I have used 41mag and 44mag out to 350 yards or so.
We have a club comp on Short Siberia at 200 yards and some of the guys use their standard 50 yard load to good effect
I have shot in the 100/200/300yard comp at the Phoenix with a 44 along side a mate with a 357.
The 357 is much better at distance being less bricklike.
I have seen people using heavy 35 calibre bullets that, when loaded, are so long you have to fire them as the round wont easily extract.
People use the silhouette bullets from Hornady and others.
Powders such as N110,H110 and W296 work well.
I do have some sierra 170gn fmj`s (8350) spare if you are interested.
Tony