Known for his custom big bore revolvers based on the Ruger Blackhawk frame, John passed away on March 19th. While we often over use and/or misapply such terms, John really was a pioneer in the realm of big bore hunting revolvers.
https://www.americanrifleman.org/content/in-memoriam-john-linebaugh-1955-2023/
It was either him or Hamilton Bowen who first produced five shot cylinders for the Ruger Blackhawk. I believe it was John, since Mr. Bowen chambered many of his revolvers in either the .500 or .475 Linebaugh. Mr. Bowen named no calibers after himself.
I never had a .500, but I did have a .475 for a little while. In one of my more "mature" moments, I came to realize I had no real use for such a gun (the same conclusion I reached with my Freedom Arms .454 Casull) and traded it off for something long forgotten.
Either his .500 or his .475 will launch 425-450 grain bullets at just over 1,300 fps. Recoil is what one might describe as "substantial". I spoke with John several times as he was building my gun. He at first refused to even sell me one in either of his proprietary chamberings - that was his initial answer to everyone who wanted one. He tried very hard to steer customers towards his five shot .45 Colt conversions, which actually beat the .454 Casull velocity wise. Certainly plenty of gun for anyone, he really pushed hard for folks to buy that instead.
Of course I wouldn't listen so he acquiesced and sold me one. He probably shouldn't have. He knew what he was talking about. He did recommend that even experienced shooters new to those calibers do two things - wear a bicycle helmet the first time you shoot it, and never put more than a couple of cylinders through it at any one session.
That proved to be good advice, on both counts. The hammer buried itself into the forehead on my helmet on my first shot. I soon learned to let it come back over my left shoulder instead of straight back. And, yes, more than a couple, maybe three cylinders through it found me reaching for the Advil when I got home.
I guess the biggest difference between John's sixgun conversions and other big bore handguns is just their "usability". They are the same size and weight as Ruger Blackhawk. Real world portable and useful. We see the .500 S&W, the massive big bore Desert Eagle, big bore single shots (no more than short rifles without a stock, really) and other less than practical "sidearms". In sharp contrast, we can wear one of John's guns on our hip, or in a shoulder rig, or whatever and scarcely even know it was there. Until we need to pull the trigger... that's where we really pay for that "portability".
So, yeah, very specialized tools for very specialized purposes. Certainly not for everyone (including me). A forward thinking "self made man" with no formal training, just an idea of something he wanted. One of the world's nicest guys, and one of the most respected in the shooting world during my lifetime. RIP, John.