Al Talbot's amazing QD mount has got me working enthusiastically on a new idea about scopes for a long-range prairie-dog rifle. This notion is based on a few fixed premises that I'll explain if you like but won't argue about.<P>� I don't like variable scopes. They're unreliable. I've tested dozens of 'em, probably hundreds, and found most of 'em changing zero too often, too easily, at each change in magnification. Anything inside that has to be free to move when you want it to move, will sooner or later move when you don't want it to move.<P>And Murphy's Law ("Whatever can go wrong will go wrong at the worst possible time") is not the worst of it. Howell's Law is more appropriate: Whatever can't possibly go wrong will go wrong sooner or later.<P>� The Talbot QD mount is outstanding in two regards.<BR>(a) It returns to zero every time you take the scope off and put it back on. Every time.<BR>(b) Once you get the knack of working this unique mount, you can change scopes in three to five seconds, easily.<P>� Usually, on a prairie-dog shoot, you get some "normal-range" shooting for a while; then all your shooting is farther out. Still later, all your shooting is 'WAY out there even farther.<P>� Using a single scope for all these ranges requires either<BR>(a) holding over, higher and higher, as the ranges get longer<BR>or<BR>(b) running the vertical-adjustment knob up and down as ranges change from near to far and later vice versa.<P>So on the high-quality .220 Howell varmint rifle that's in the works, I'm going to try using three fixed-power scopes, with three different magnifications for three discrete shooting ranges � an 8x to maybe a 10x, a 12x to maybe an 18x, and a 24x to maybe a 32x � depending on what's available that I can afford.<P>I've just been fumble-figgerin' trajectories with the QuickTARGET software, to see what I could work-out in theory first � using the 75-grain Hornady A-Max at a muzzle velocity of 3,550 ft/sec. This exercise has been most interesting.<P>If I zero Scope A at 257 yards, for example, the point-blank range for a two-inch vital height would reach clear out to 298 yards. Not bad for "normal range." The bullet shouldn't rise more than two inches at 153 yards.<P>A three-inch vital height would require zeroing at 296 yards to extend the point-blank range to 345 yards, and the bullet shouldn't rise more than three inches at 164 yards.<P>A four-inch height would require zeroing at 328 yards to extend the point-blank range to 384 yards, and the maximum height of trajectory (four inches) at 186 yards.<P>Listing all the options for all three scopes and all three heights of the kill zone would take too much space here, so let's jump to the figures for Scope C set for a vital or kill zone four inches high.<P>Zeroed at 517 yards, Scope C would allow me to hold for a four-inch height out to 548 yards, with the trajectory highest (within this range segment) at 480 yards.<P>If I settle on the four-inch-high kill zone as my standard, I can zero Scope A at 328 yards and use this one setting out to 384 yards with no more than four inches hold-under at 186 yards or four inches hold-over at 384 yards.<P>For shooting from 385 to 480 yards, I'd zero Scope B at 440 yards and not have to hold-over more than four inches at 480 yards.<P>For shooting from 480 yards to 548 yards, I'd zero Scope C at 517 yards, and the trajectory should be no more than four inches high at 480 yards, no more than four inches low at 548 yards.<P>The usually unacknowledged error in this kind of trajectory calculation is that while the theoretical trajectory is pretty much what the hard numbers say it is, the actual trajectory of each individual round is going to be somewhat different � and the differences are correspondingly larger as the range increases.<P>But this error is a matter of each individual trajectory itself, not the scopes' actual zeros and "pure" point-blank ranges.<P>This method just might make a better long-range hitter out of this ol' coot. Checking it out will most interesting, I think.
