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这个人的“实验”是off hand shooting, 而且是20码， 还有其他因素在里面， 所以我强烈怀疑他测试的准确性.
很多老枪没有可调铁瞄。 所以必须靠调整手装弹来把point of impact zero到point of aim上， 和我们校枪正好相反， 但这也是一个常见的practice.
http://castboolits.gunloads.com/ ... l-Dwell-Time-Needed
“Example #1: I have a 4 5/8" Vaquero in .45 Colt caliber. One certain 325gr boolit over 19.0gr of 2400 powder would strike the target 4" low in 25yds, 18.0gr resulted in the boolit striking 2" below point of aim, 17.0gr had it shooting to 1" below point of aim. The dwell time is shorter with 19.0gr of 2400 powder than it is with 17.0gr, so as the gun is fired, recoil causes the muzzle to rise, but since the boolit is traveling fast, it exits the bore before the muzzle rises far enough to shoot to point of aim. With the 17.0gr load, the boolit is traveling slower, and the muzzle has more time to rise, and it shoots to a higher point than the faster boolit. Developing loads for a single action which will allow it to strike point of aim is called "bringing the boolit to the sights." This is how you use dwell time to make your gun shoot to where the sights are pointed.
Example #2: I have a 7 1/2" SBH in .44 Magnum caliber. I wanted to develop a load with the very fine Lee C430-310-RF boolit. Knowing there is no way I will get 1250f/s velocity with a boolit this heavy, I anticipated the rear sight would not adjust low enough to sight the gun in with this load because the increased dwell time would have way more muzzle rise than the sights were able to compensate for. Upon shooting this boolit over 16.0gr of 2400, I discovered that I was right, and it was hitting the target a full 5" above point of aim at 25yds. Not being faint of heart, I took the gun to a vise and very carefully filed down the rear sight blade until it was even with the body of the sight, then refiled the notch in the center of the blade. Now the gun shoots beautiful groups, directly on top of the front sight blade, with these heavy boolits.
So to explain recoil dwell time, it is not describing how hard or how sharp the felt recoil is, it is describing the amount of time the boolit is in the bore, which affects the point of impact due to the movement of the firearm in the shooter's hands during firing.
In general, lighter boolits have less dwell time than heavy boolits. A higher velocity load will have less dwell time than a standard velocity load. How fast or how slow the powder burns isn't the determining factor, it's how fast the boolit is driven out the muzzle which determines the amount of dwell time.”
他的.45 colt打325gr弹头， 装19gr的时候低四寸， 装17gr的时候低一寸， 少了两个grain的火药， 弹头慢了许多， dwell time增长， 弹着点在25码提高了三寸。 |
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发表于 2014-3-17 08:15
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千斤顶
发表于 2014-3-25 11:35
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多谢指教~