Clark,
Thanks for the heads-up on the Corbon 255. I have not purchased any factory 460 loads. If Corbon is running their 255's at 1100, then perhaps my 250's at 1150 are not insane. I do know that it usually takes me getting the 250's to 1200 to start to see the brass signs that I get with a 230 at 1350. I find it odd that GA was having problems with 230's setting back, as I thought these were XTP's, and all XTP's feed like butter in my guns. The only one that is on the edge of rough feeding is the 240 XTP mag, and its nose profile is significantly different than the 230 and 250 non-mag XTP. I would wager a bet that if all 460's out there were built from scratch, and properly fitted GA would not have had setback issues with the ammo. I think the obvious downside to a drop-in conversion is that in reality no 1911 parts are really drop-in. Certainly a bit of dice rolling going on.
Hunter, on the other board confirmed my thought about velocity with Johnny Rowland. What he (Rowland) was after was pure velocity, probably as a marketing tool. From performance standpoint, with hunting in mind, a heavy wide properly constructed lead bullet will penetrate for days even at 900 fps. John Linebaugh, Mr. BIG when it comes to insanely wide and heavy bullets at light speed has written extensively about how well wide heavy bullets perform at moderate velocities. The problem here is that it takes a more "sophisticated" hand gun hunter to sort through a lot of this. Heavy, wide and fast is an easy sell. Light, wide and fast looks good as well to most folks. Heavy, wide and slow usually takes seeing to believe.
In my lengthy 460 testing, I have come to worry less about the slide, and more on the frame and barrel. As to destruction, I have sheared one barrel lower lug, and cracked one frame. On the cracked Colt frame, a used S70, I went on to shoot probably a thousand additional 460's before retiring it. The crack at the dust cover got to a point, and then never got larger. I only recently retired this frame from 460 shooting, as I have a new S70 SS gun that I am building. On the sheared lower barrel lug, as I have written before, was a destruction test confirming that the Clark comp may be needed. I had a spare 460 kit that I removed the comp, and polished the threads smooth. Inquiring minds want to know kind of thing.
I am with you about JMB design. I like the series 70 for the slide, as the lack of lowering and flaring might help with slide life. Haven't a clue, but makes intuitive sense. Same with the mags, for me it is 7 round Colt mags, period. And in dealing with setback issues, I am running a 20 pound ISMI recoil spring, shock buff, EGW fps and 25 pound main spring. Trying to keep the feeding side of the cycle closer to stock.
And for me, what makes the 460 attractive as an option is that I am not hung up on the life expectancy of the gun. While I am not made of money, I enjoy the shooting and hunting benefits of the 460 enough that if the gun gets "broke" in something less than the 50K that folks expect from a 45acp, so be it. This is why I have a few spare Rowland kits in hand, and picking up a new Colt was pretty easy. I would caveat that statement with your concern about the slide. I try and not do anything that could endanger me, and I do keep a sharp eye on the gun. My 460's get detail stripped a lot. And, I have a pretty good handle now on what full throttle loads do to the brass and gun. I have throttled back a bit now.
Craig