Hmmm..Just thinking about more horsepower !

Pretty sure that's the limit. JD jones did a .600 something based on the .577 case. Someone one here has one if I recall. As one who has some hard kicking #1's I can't really imagine a .577 without a serious brake or some weight added....

Yup

Integral Brake make a Big difference ! I had 8 pd 600 Overkill that kicked less than my 13pd 600 Double due to the brake and proper stock designs...

well, if you used 577/500 brass and shellholder with 577 ne dies, its a smidge smaller than the 577NE

And our 585 HE goes in perfect in a #1 without

hogging out metal from the sides of the feed trough

like what has to be done with cases with 577 size rims.

That metal removed is part of the shoulder supporting breach block.

And a Ruger #1 extracts regular belted cases like our just as good

or better than rimmed 577 cases. And we have barrels of cases.

Can run full pressures, get 13,000 ft lbs..Ed