Well, I've been sitting on a little secret for almost a year now, and perhaps its time I finally tell. I had the pleasure of shooting Buck's famous prototype rifle in 454 Casull last April in Hotchkiss, CO. Its current owner, who resides in Alaska, is a friend of mine from another forum group, and he graciously let me pay to have the rifle shipped back to the “lower 48” for me to test and write about.
The rifle's history I will leave to Buck himself to speak of if he wishes. It is a rather painful journey down “memory lane” for him and he may not want to. He did have some remarkable hunting experiences with the rifle that he may share, however. Therefore I will only speak of my limited experience shooting the rifle at the Friend's of Billy Dixon Ultra Long Range Shooting Facility with my friend Tym Hurst.
The gun is impressively heavy and attractive in its contours and design. The wood is beautiful, the metal-to-metal fit outstanding, and the wood-to-metal fit still pretty tight although the wood has dried and shrunk some over the years. The metal had a slight patina on it that just added to the rifle's appearance. It had what appeared to be a medium-heavy octagon barrel that made it very steady to shoot off-hand. The trigger pull was very crisp and broke cleanly at what felt like an easy 3 lbs. From my first try I was able to hit steel targets at 300 yards repeatedly with little difficulty and my general impression was that it was a fantastically easy to shoot and accurate rifle.
There were some functional problems with cycling ammunition reliably but you have to keep in mind that this was a prototype, the first incarnation of Buck's design, and as it turned out, the only one ever built. I'm sure if Buck had had more financial resources, more development time, and the ability to make more prototypes, those bugs would have been worked out and the end result would have been a truly outstanding rifle.
In the end, my friend Tym and I were able to put about 10-12 rounds through it before we noticed a very small crack starting in the butt stock or forend, I honestly do not remember. We immediately stopped shooting but took many pictures of this splendid rifle.
It sounds like a rifle similar to Buck's, but not based upon his designs, is going to be produced by Big Horn Armory chambered in 500 S&W magnum. Perhaps we shall also see that same rifle chambered in 454 Casull or 460 S&W some day.
Meanwhile, Buck's prototype rifle stands as perhaps one of the earliest examples of chambering the mighty 454 Casull in a levergun.
But I do know of some others. But that is another story..........
As always, thanks for listening.
-Tutt
Thanks for sharing, and as always, for the pictures! 
I know Buck has written about his tests of the Win 94 and Marlin 336 and the .454. May be he will be along to share on this rifle.
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Puma's weigh about 7 lbs and that 454 is the equal of a 45-70 with a 300 grain bullet, so do the math! Also, the factory recoil pad is a joke! 