I tried posting this earlier but obviously had finger troubles and it didn't post.

This post will be a little shorter as I don't want to type that all out again!

So, Greener actions have been barrelled in 577 2 3/4" NE and 577 Snider with big smokeless charges. DoubleD has a Greener in the former.
As much as I love big bores and have thought about .585" and .620" cartridges in a Greener I love .458"'s so am thinking of one to replace my 45-120 Uberti High Wall. Since the Martini is my favourite action it seems like a good shout.

I am thinking Greener action, .458" barrel chambered in 577/450 (.458"), .458" 577/450 dies and load up to 577 Nitro pressures (2450 Bar/ 35,500 Psi), an increase of 10,000psi over standard.
Quickload predicts some very promising numbers.

Anyone done this or have thoughts?