I have a bit of experience with them. In their day they were considered THE long range rifle in Australia. They were recomended for everything Australian except crocodiles and buffalo, though even the buf was considered fair game by some at that time.

Couple of points about the ammo. I

I favour running them through the 303-270 dies first, as I have destroyed as many as I make trying to go to 303-25 in one pass. Might just be that I am impatient and rush it, but seems to happen.
The neck seems to work harden badly also. I am in the proccess of pulling several hundred down for someone with a view to annealing the cases. Most were splitting on the first firing, and over time they have started to split without being fired. Accuracy has also been erratic, and I suspect this is due in part to the neck tension being all over the place. All were new commercial cases.

A final thing to look out for is old converted military brass. Much of this was created by pulling the bullet and sizing the case, complete with original cordite in place. Having seen much 303 being used on the range, I have observed missfires, hangfires, variations in the bang, and a strong ammonia smell from many of these rounds. They also tend to crack in the neck, the shoulder and along the body from the web. How a similar charge would behave in a significantly reduced bore is something I feel no need to experience personaly.

They were touted as the perfect kangaroo and dingo rifle for the open country. I would be happy to use it against most animals in Australia (not buffalo - some of those old blokes were a bit game in days gone by), as long as there was more hunting than shooting, that is get within range and put the bullet in the right place.