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Bighammer

The answer is NitroX's suggestion of the 450 Rigby.

But it will be more trouble.

However it would also be my own choice over the 458 Lott.

I have nver owned a 450 Rigby or Lott but I have owned two 460 Wbys and a good shooting mate had a 450 Ackley. As you probably know the 460 Wby and 450 Rigby are the same except the Wby has a belt. But there is a more important difference that favours the 450 Rigby and that is the 460 Wby has huge freebore which makes reduced loadings more difficult to work with.

The 460 and 450 do 458 Lott max ballistics like a walk in the park. They use a far greater variety of powders and just much better to play about with.

At the low end I use to use 28 grains of Dupont Hi Score 700X with 400 grain Speers in the 460 for just over 1300 f/s and accuracy was superb in both 460s. 85 grains of 4064 did just over 2000 f/s with 500 Hornadies with top accuracy (and no fillers in either load) and that 85 grain load was 20 grains below maximum with 4064 in the 460.

A 450 Rigby will give you full 458 Lott ballistics with every powder from 2207 through to 2213 and 2217.

Due to the lack of huge freebore where the 450 Rigby will be better than the 460 is for load that are at the higher 45/70 range. With a 460 you can come down a bit under 458 Win ballistics with beautiful results but once you go under that you get hangfires, unless fillers are used. So wth the 460 the next stage down is with shotgun powders and 1300 f's speeds with 400 grainers. But I don't think the 450 Rigby will be like this becuase of the lack of huge freebore, which causes ignition problems in the 460.

If we couldget the American Accurate Arms powder 5744 (I think that is the number) then the 460 would be OK at the higher 45/70 levels. That powder is made like a shotgun powder in that it is bulky and easy to ignite but had a burn rate about like 4227 or 2205.

Brass for the 450 Rigby is a bit inconvenient as it is a 416 Rigby necked up and improved. Probably the best bet would be to neck to 50 calibre and then run through the 450 sizing die which would form a little shoulder on the bottom of the neck. If 416s are necked straight up to 450 I don't know if the headspace will be OK or not as I have a feeling the body of the 450 Rigby is slightly longer.

But you won't need many cases sine 99.99999999999999999% of you loads will be at very low pressure.

To do a 450 Rigby in Australia I think I would start with a 416 Rigby in the Ruger. However, I would talk to someone like Bob De Vries about rechambering a 458 Ruger given the integral quarter rib etc. and his feelings on getting feeding right from 458 Win to 450 Rigby.

In a nutshell, the journey to 458 Lott is a lot easier and practical than the 450 Rigby.....but once there the 450 Rigby will be much better to have and play with.

Mike