newbie question: why no recoil travel calculator?

Walter Haas

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I'm new to shooting as of the last two weeks and I'm trying to make sense of one point about body position and rifle position. I keep seeing the point emphasized that the backward travel of the rifle during recoil needs to be free of obstacles that would alter the barrel alignment before the bullet exits. What I don't see anywhere is how to calculate what this distance is for my rifle and bullet. That strikes me as strange, that the rifle travel is important but there's no calculator for what that distance is.

My first guess was like a quarter inch. But after doing the math its like 7/100ths of an inch for my rifle and bullet, which are 17 lbs/24 inch barrel, and 168 grain bullet w muzzle velocity of 3000 ft. I'm using rough values to see if things pass the common sense test and they're not.

I'm assuming average velocity through the barrel while under force is half the muzzle velocity. Bullet and rifle see the same force profile even though that force varies as bullet travels from breech to muzzle.

I'm assuming conservation of momentum using [momentum of bullet at muzzle]=[momentum of rifle]

mass(bullet) X velocity(bullet) = mass(rifle) X velocity(rifle)

Its just common sense, right? If the bullet is going 3000fps at the muzzle the average velocity in the barrel is 1500fps since it starts from zero. And if the barrel is 2 feet long then the bullet travel time is 2ft/1500seconds which is 1.333 milliseconds which is a believable, common sense number.

How far back can the rifle go in 1.33 milliseconds? I get 7/100ths of an inch, which is trivial. So this idea about making sure the gun has recoil travel doesn't add up unless my travel calculation is wrong, which is why I'm looking for a calculator.
 

Dthomas3523

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Not sure where you’re seeing it come up that nothing needs to get in the way before the bullet exits.

The common agreement is that it’s possible to move the muzzle at the time of trigger press via several different ways (trigger not pressed straight back, rifle slipping on shoulder, etc).

I see no reason to get anymore technical than that or a calculator.

Practice proper fundamentals and don’t do anything that moves the rifle inappropriately.
 

Dthomas3523

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Before the argument comes up that follow through doesn’t matter because the bullet has left the barrel, I’ll provide this example of another game where follow through is important:

In pool, you need to practice good follow through after striking the cue ball with the cue. In theory, once the cue ball has left the tip of the cue, nothing else matters. Which is true. However, if you try to do anything (like stopping the cue as soon as it makes contact) you will make a bad strike on the cue ball.

Same thing with a rifle. While yes, the bullet leaves the barrel too fast for you to influence it without movement after the trigger press (for the most part), you need to practice proper follow through to avoid doing anything prior/during the trigger press to influence the rifle negatively.

Follow through confuses people because they feel like it’s speaking solely after the trigger is pressed. Follow through and recoil management is something you practice the entire act of shooting.
 

Fig

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This isn’t calculated because it doesn’t matter. If your fundamentals are good you will have have consistency and repeatability. Consistency in shooting technique means precision shot to shot and that leads to accuracy. Length of recoil would be different for everyone.
 

Dthomas3523

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There is also lock time that needs to be considered. There is milliseconds between the trigger press and the firing pin striking the primer. There is even more time in a gas gun between the trigger press and the hammer hitting.