P.O. Ackly and angular velocities
Personally, I think this Greg fella won't be a happy camper. The real question here, isn't how much linear velocity he will have at 300+ yds, but rather what angular velocities will cause the Barnes TSX to mushroom, way out thar? This tain't an easy thing to answer. Ray Speer told me face to face, years ago, that his rifle bullets would all retain, at minimum, 92%+ of their muzzle values of angular velocity. And this was why all of his published terminal effects were shot into wet pulp lap, at whatever ranges. The Barnes solid copper bullets won't blow up like those 220 Swifts did in Ackley's recounted Burro culling, at 500 yds..Those burros dropped in their tracks from a dinky 22 bullet traveling at no more than 500 fps.. But, that 45 gr. Swift bullet wasn't anything like a 22 L R. rim fire, either. It was spinning at near to a quarter of a million RPM's. It killed by cavitation in the body cavities of those burros. I have no idea if the new Barnes 250 TSX will spin fast enough in a Marlin 45-70 barrel, to replicate Ackley's findings. But Mr. Speer and Dave Andrews were talking with me at Dave's desk, and I got something else out of those two learned gentlemen. The bullet sheds all of that 92% rotational energy, about 9 to 11% of the total foot pounds, by the time it stops in flesh. They don't continue spinning like a child's toy top. So everything with any terminal energy is instantly expended inside the critter, if there's no exit wound. So, if Greg uses the top borderline Barnes loads in a twenty two inch barreled Marlin, he may get the rotation needed to store enough energy to do dirt to a large non violent quadruped. But its the boundary circumference of the bullet that sheds all the energy. And it's this which makes the classic football looking cavity in ballistic gelatin. The quicker the mushroom, the stubbier the football. What P.O. Ackley wouldn't have known, back then in the thirties, is that it was a one-two punch. First, the bullet disintegrated into a mist of bloody pulp, and instantly killed the burro, time after time. Secondly, with the dinky 22 entrance wound puckered shut, a cavitation vacuum sucked about a million or so micro snapses open in all of the burro's capillaries. This opened all of it's blood vessels towards the center of the dead body's cavity, right at the wound site. So, when those animal control officers did their necropsies, within the hour, they found all of the dead burro's blood coagulated into what looked like an extra gelatinous organ. But I believe that the burro's central nervous system had to go defunct on the first outwards blow, in order to relax in death, and then let that tiny disintegrated bullet, do it's bloody deed. By definition, those solid Barnes TSX's, won't simply disintegrate, and the expanding nose petals will slice, rather than explode. And if Messrs. Speer and Andrews were correct, they will only slice until their forward motion stops. So, no football like expansion, but only a reasonable wound channel, and most probably, an exit wound. Some of the real old timers were onto this when they wrote about round balls, "drilling", through beasts. Once in my foolish youth, I shot a .50 RB into a seasoned larch 3 x 8 plank at 140 yds.. Then I capped another one with the same charge, into it from 6 inches away, at 6 o'clock. The long range ball penetrated almost as deep, as the one from six inches. IIRC, it was 2&3/4 inches vs. 2&1/2 inches, when I sheared the plank open, through both bullet holes, with a splitting wedge. Both of those RB's were still mostly round, too. Who woulda thunk? My ancient smokepole has a 1 turn in 48 inch twist, and I was insanely using 120 grs. of FFG. After I later had it re-breeched, I was told to never go over fifty grains of FFG. So, I hope Greg stays as lucky as I was, way back then. But it's going to be a bear for him to document results with these lightweight TSX's in his 45-70 Marlin. With Barnes being Barnes, he will have to shoot up some mighty big critters, to photograph the destruction he foresees. But just like with P.O. Ackley's account, it will most likely take the shape of an extra gelatinous like organ recovered in field dressing his animals. IOW, I too believe this approach is all wet. These light bullets have to disintegrate in order to cause this level of lethal cavitation. So, using Barnes TSX's seems to me to be completely counter-intuitive. Maybe Ol' Greg should be playing with paper patched .457 Ruger Old Army conicals? This is at least, pretty close to the original Black Powder Express loads. Those old rifles had really slow twists, to get any accuracy. One of my wife's relations had an original, factory Win. 86, in 45-90 Express, that weighed an honest 20 lbs. Now, that was a Buffalo Gun! But I'm also pretty sure that it only had a 1 turn in 30 inch twist. Now if Barnes can cook something up with an aluminum nose, something like the old SilverTip, but with the TSX's solid metal shank, that's as long as a 350 grain jacketed lead bullet, I would be willing to try some in my Guide Gun, albeit, with reasonable powder charges. But then the bug bear is that the bottom round in the mag tube is canted, to help it make the turn into the magazine. This opens a pandora's box with any hard metal tipped bullet. So, then the aluminum tip may need it's own flex tip to boot. But since it's the length of the bullet that determines the twist, not the weight, there may be something to this, down the road. In the mean time, a paper patched, pure lead, 45 Old Army 250 gr. conical, may suffice for Greg's 45-70 Gov't experimentation, with really light for caliber bullets, up above 2200fps.. So I'll happily leave this idea to him, and stick to my Speer 400gr. Jacketed bullets, at 1850 fps, for now.