Test rifle is a CZ 550 with the factory barrel shortened to 21", resulting in a much better handling rifle. The question was how would the shorter barrel affect velocity.

All loads new WW brass, CCI mag primers, Barnes FN/banded solids. The 450gr solids were seated and crimped in the second groove from the front for an LOA of 3.425". The 500gr solids were seated and crimped in the third groove from the front for an LOA of 3.565" . This method was used to see if the 458WM lack of case capacity could be overcome without excessive powder compression and still obtain satisfactory velocities. The CZ has a cavernous magazine which allows this method to work, all rounds fed and chambered just fine.

All rounds were put into my culling belt and left in the sun for about an hour (95 degrees) prior to chronographing; they were almost too hot to handle. 5 shot strings, results as follows:

1. 77gr H335, Barnes 450, av 2230 fps
2. 79gr H335, Barnes 450, av 2265 fps
3. 75gr AA2230, Barnes 450, av 2235 fps
4. 79gr AA2230, Barnes 450, av 2300 fps
5. 72gr AA2230, Barnes 500, av 2105 fps
6. 76gr AA2230, Barnes 500, av 2160 fps

All rounds fed, chambered and extracted just fine, the primers still had plenty of radius on them, no flattening at all. In my rifle the above loads are good working loads. Don't give up on your 458's just yet.

The usual reloading caveats apply. Good luck and good shooting, Russ Green.

Well done. And only 21". Hardly fashonable though.