The Rossi Model R92, a lightweight carbine for Cowboy Action, hunting, or plinking! Includes Rossi manufactured Interarms, Navy Arms, and Puma trade names.
Reese-Mo wrote:At short distances, a faster bullet will shoot lower, due to less time in a rising barrel. At long distance, the slower bullet will have more "drop".
Not quite. The first part is an old wives tale that keeps getting retold.
All else being equal, a faster bullet will always drop less (impact higher) than the same one fired slower, because gravity has less time to pull it down. The length of the barrel has no direct effect on the trajectory (other than a longer barrel usually gives more speed to a bullet because the gas pressure has more time to act on it, and a faster bullet will impact higher).
Trajectory can be a little counterintuitive, not least of which because the bullet starts off by both rising and falling at the same time, depending on how you look at it.
My understanding is that the dominant effect is barrel vibration, assuming that it’s not a bull barrel. The shock wave of the ignition travels much faster than the bullet. Then, recoil is partly due to the acceleration of the bullet, and partly due to the escaping gasses as the bullet leaves the muzzle.
Reese-Mo wrote:So I guess the US Army got it wrong?
At >>_SHORT_<< distance is the key. General Hatcher explains it in his varipus texts.
Easy there... I'm not trying to get in a contest over this; just explaining some physics principles. If you'd like to post some links to the specifics that you're referring to, I'd be happy to take a look and see where the disconnect is. Maybe we're just tripping over semantics.
I don't believe Hatcher's Notebook is online. However, the basics of it are this:
As you mentioned, time is a factor. Naturally, the bullet can do nothing more than drop, more or less at 32fps^2. It does so starting as it leaves the muzzle, and only "appears" to rise, due to the relationship of actual departure angle, offset of the sights, and target distance. On that, I think we can agree.
However, there is also barrel time. Larry Kelly made a good living providing his EDM "Mag-Na-Port" services to riflemen (and pistoleros) for decades, and that company is now in his son's hands. The diversion of gas upward would counter (through the same principle as rocket nozzles) the rise, or "flip" of barrels. And therein is the point. A faster bullet is in the barrel for a shorter time than a slower bullet - all else being equal. As the muzzle rises, the slower bullet is in that barrel for a longer time, and the barrel will rise more, increasing the angle of departure, before the bullet exits the muzzle. And also, naturally, as the distance to the target increases, the faster bullet does get there in a shorter time, so therefore its drop is less.
This is very evident in handguns, where muzzle flip is more pronounced, although it also exists in rifles. Take your typical fixed sight .357 magnum revolver, say, with a 4 inch barrel. Just plain jane medium gun. Shoot some 158g .357 full house loads in it. Now shoot some 158g mouse fart loads. The mouse farts will always print higher on the target, for the reason I explained.
Interesting point most folks overlook. Drop a bullet at the firing position at the exact instant another bullet is fired parallel with the ground. Both bullets hit the ground at the same point in time.
Hatcher had the ability to make the complex understandable, and if you can get an _old_ copy of this notebook Vol1 and Vol2 its well worth it. The "newer" prints, are expensive, and literally poor photocopies of the original, which had great and clear/legible illustrations and photographs done in faultless halftones. The new books are fuzzy pictured at best. My favorite part of that book is how Hatcher explains the means by which the USA fought two world wars with the wrong ammo issued throughout all the armed services!
And, no hostility intended, we're all on the same team!
I've read a couple of Hatcher's works including his Notebooks but it has been a while.
I will admit that the Velocity vs. impact on target related to 'time of the round spent in the barrel' always bugged me. It would seem that would ALSO be a function of the flexibility of the mount/shooter's hold, and there's a heck of a lot of other factors that wold seem to go into the equation like recoil differences fed by how you vary the velocity like powder type and charge ...
Using your example of .357 Mag loads vs. mouse phart loads. I am going to have to take it out to the range and give it a test sometime I'm board BUT in my limited experience with similar loads, say full bore 200 grain hollow points vs. 200 grain 'match' powder puff loads out of a .45 ACP I have not noticed the powder puff loads printing higher. The extra time in the barrel seems to be offset by the fact they simply have no recoil to speak of so the gun isn't rotating or recoiling nearly as fast. The low bore axis might help. In rifles you get a much better hold and potentially more stable weapon system vs. much more time in the barrel
I own a magnaported .44 as well as a compensated and a standard barreled vs. all 6" barrels although I think the integral compensator adds a 1/2".
The Magnaporting is cool but it is mostly good for reflecting the noise off the roof of the pistol shed and onto other shooters. A good fitting grip is worth a whole lot more in my opinion. (unless of course the reflected shock wave messes with the other shooter's ability to hit the target...)
----------------------------
The discussions on the couple gun boards I spend my time on tend to be pretty mellow.
My last spirited discussion on a gun board happened when a gent decided to take issues with something I'd said with regards to short barreled weapons in rifle calibers.
MY statement was essentially that recoil of a short barreled weapon in .308 might actually be LESS than firing the same cartridge in the full up rifle barreled version of the weapon. A couple weeks after the statement this expert opined that was simply WRONG and that all things being equal the recoil of a shorter barreled weapon would ALWAYS be MORE than that of the same weapon with a longer barrel.
The disconnect in that discussion was exactly WHAT was equal.
My point was that shooting the exact same .308 round in a pistol barrel wasted much of the energy in powder that was either unburned or was burned outside the barrel. In such a case the recoil might actually be reduced compared to the same exact round fired in a gun that was a half pound to a pound heavier because in that weapon the bullet developed as much as 1/3 more velocity and all the energy of the powder was going into accelerating the bullet and combustion gases down the barrel and the gun into the shooter/support.
His point appeared to be that if you had the same muzzle velocity of the bullet and gases exiting both systems you'd get more felt recoil in the lighter weight weapon. Exactly how the exact same .308 cartridge was supposed to produce the exact same velocities whether the barrel length was 10 or 12 inches vs. 18 or 20 or even 24 was left for the student to prove.
I posted my proof from the mass and energy equations to which he would post an equation where he didn't bother to define any of his variables. Eventually I ran through my points in summary to which he admitted each and every one could be true and reiterated his equation of undefined variables and he never once posted an example of real world figures that would get his 'all other things being equal'. I'm moderately convinced English was not his first language and that he may have been picking a metaphysical nit by taking something out of a context he didn't get rather than simply trolling.
Archer.... everything you said is true. There are tendencies, not absolutes, as you noted, due to hold, due to shooter, due to phase of the moon... all that razz-ma-tazz. And, what you also said is more or less true, especially with an autoloader because they have only a certain range of function as far as projectile speed goes.
I will give an anecdotal report of our "range reloads" back in the day, those being very light. Guys would shoot a box or two of our .38's (they were 140ish grain as I sort of remember... not very light, certainly not heavy). They'd fiddle and futz with their sights cranking 'em all the way down. "Your loads shoot high". I'd give 'em a few of our more potent (and barrel leading!) 357 rounds, which were really a 38+P (sort of). They shoot too low. Can't please some folks, and we were only a 50 foot indoor range, and jacketed magnums at about 40 feet.
Mag-Na-Port never really impressed me, although I ported a few of my own handguns. Works way better in a rifle, I'm guessing due to higher gas pressure, and higher volume of gas. Kelly's trapezoids and his "experimentation" was more for uniqueness and ease of production from the little I know. My shop did porting on an EDM machine a few warehouse bays down the line, and at times we ground electrodes that were trapezoid, round edge... no real difference from what we could tell. Round edges are a pain tho, due to erosion of the electrodes, while trapezoids (with radiused edges) are visually more forgiving as the electrodes wear. We'd grind six at a time about 3 inches long and use one as a starter, one as a medium cutter, and one as a finisher. You can shorten 'em to get clean electrode again, but after a while, #1 goes by the wayside, 2 becomes 1, and 3 becomes 2. You bring in #4 to sub as a new 3, and so on. I even cut Colt King Cobras to have vented ribs on top like a Python (or Pitheon as we'd call 'em). That was way before Colt got the idea to do the same on some.
The bullet has left the barrel before most of the recoil induced muzzle rise occurs. Not saying there’s none, but not much. And not so much that differences in muzzle velocity will be apparent, especially at short ranges. Until somebody does a controlled experiment with some rigorous statistical analysis, I’m not buyin’ it.
Porting, in particular, has very minimal effect until the bullet has left the muzzle. The purpose of porting is to speed follow-up shots, not improve accuracy. It does have the additional benefit of annoying your range neighbors.
Well.... On a rifle, up to 60 percent of recoil energy is the resilt of gasses leaving the barrel, so porting does help in that regard. Its the 40 percent that would effect the bullet pkacement.
Nope, the mass of the rifle is much greater than the bullet, so the response is slower. The great majority of motion due to recoil occurs after the bullet is clear of the muzzle.
