http://www.24hourcampfire.com/buhmiller.html Seems John Buhmiller did the 577 on the Gibs case many moons ago. Question is how did he do it? Swage a belt like the 577 BME or a simple taper no shoulder or a minimal taper tiny shoulder????

John Buhmiller was a friend of mine and we compared notes on wildcat cartridges from time to time. My version of a rimless .577 was simply the .577 NE case with the rim turned off and a rebated rim machined in its place. The case length was reduced to 2.5" and just enough shoulder provided to headspace on. I suspect that John's version was not much different.

I had no problem achieving .577 NE performance with a 750 grain Barnes bullet and 120 grains of 4895 in my Enfield actioned rifle.

Thanks for posting.
I bet you could tell us a lot about his work and yours as well. Gibs brass necked to .585" leaves about a .615" neck diameter. That leaves 20 thousandths to have taper and shoulder. That's why I designed the 577 BME to have a belt and minimal taper. The 577 case measures about .660" on the casehead so more to play with compares to the .635" actual casehead of the Gibs brass. Would be great to hear of your favorite big bore carts you and he played with. That cart you mentioned sounds similar but a shorter version of the 577 Nyati.

Buhmiller was a big bore wildcatter par excellence and without peer.

His exploits include creating and field testing, in Tanganyika, on heavy, thick skinned game, the first .460 Weatherby, .500 A-Square, and .577 Gibbs.

Not to mention creating cup point solids.

He did all of this over fifty years ago.

I'm curious who could find his dimensions on the 577 Gibs. Who has his old rifles?