groups dropping advice

[BoydAllen]

Show me. Even though I'm not from Missouri.

Bart, I guess that I did not do the quote correctly in my post. I failed to attribute the quote that I disagree with. Perhaps you meant to ask him to show you and it just came up like your were disagreeing with something that I had originally written. I think that that is what happened

 

[Bart B.]

Bart, I guess that I did not do the quote correctly in my post. I failed to attribute the quote that I disagree with. Perhaps you meant to ask him to show you and it just came up like your were disagreeing with something that I had originally written. I think that that is what happened

Yes, that probably happened.

I agreed with your remarks.

Complicated things complicate their discussion. We can't see the muzzle axis vibrating several hundred times per second and its axis angle back and forth across a few MOA spread.

 

[dellet]

"Finally, no firearm recoils to any substantial amount until the bullet leaves the muzzle so any firearm movement isn't caused by the bullet until the bullet exits the bore. Most rifle bullets leave the muzzle somewhere around 1 ms after the powder charge ignites and studies show that recoil movement doesn't usually happen until around 10 ms which means that the rifle starts to move when the bullet is about 2.8 feet beyond the muzzle (assuming a muzzle velocity of 2,800 fps).

If this was true then bag slickness would have no effect on accuracy. It would not matter that a rifle stuck a bit and then slid, and it does. Also, stock angles would not matter and they do. For example, taking this out of benchrest a bit, a friend has a custom Martini Cadet that has a 3" wide forend and has been converted to .22ppc. The toe angle of the stock is extreme by target rifle standards and he was having some consistent vertical issues. I noticed that he was not shouldering the rifle and advised him that because of the toe angle and probably inconsistencies in how the rifle recoiled from shot to shot that he probably would get better results if he held and shouldered the rifle. It worked. I learned this from a friend who shoots a schutzen rifle with a similar toe angle. Shooters who shoot free recoil tend to pay a lot of attention to things that affect how a rifle slides on the bags. If the rifle didn't move until the bullet was clear of the muzzle, then that should not matter. When shooters are not constrained by the rules they generally choose to have a flat butt angle for rifles that will be shot free recoil. I think that this is based on experience. In my experience, studies may or may not be conducted in a manner that yields results that are consistent with real world data. When there is a conflict, I do not automatically assume that the study is right and experience is incorrect.

Maybe I have this quoted correctly.

Question for BoydAllen.

Is part of the reason for keeping barrel movement in line with the bullet path, because the bullet basically needs to out run the gasses and turbulence in the first few inches/feet of flight?

Basically pushing straight past the base of the bullet instead of at an angle that would potentially disrupt flight.

 

[BoydAllen]

I don't know if that is the case, but I think that having the centerline of the bag tracking surfaces parallel with, or coincident with that of the barrel(when viewed from above) tends to minimize the effect of shot to shot differences in rifle movement before the bullet clears the muzzle. If the stock were at a significant angle to the barrel (again as viewed from above) I think that during recoil a force would be introduced that would produce sideways pressure on the barrel that would complicate its motion in a way that would be undesirable. I think none of this matters nearly as much if you are shouldering and holding the rifle, and matter most when shooting free recoil. IMO most "ordinary" rifles should not be shot free recoil, or even close. They may have too much recoil for their weight, have triggers that are too heavy, stocks that are not properly designed for that shooting method, and not be balanced properly.

 

[Webster]

[QUOTE="Finally, no firearm recoils to any substantial amount until the bullet leaves the muzzle so any firearm movement isn't caused by the bullet until the bullet exits the bore. Most rifle bullets leave the muzzle somewhere around 1 ms after the powder charge ignites and studies show that recoil movement doesn't usually happen until around 10 ms which means that the rifle starts to move when the bullet is about 2.8 feet beyond the muzzle (assuming a muzzle velocity of 2,800 fps).

If this was true then bag slickness would have no effect on accuracy. It would not matter that a rifle stuck a bit and then slid, and it does. Also, stock angles would not matter and they do. For example, taking this out of benchrest a bit, a friend has a custom Martini Cadet that has a 3" wide forend and has been converted to .22ppc. The toe angle of the stock is extreme by target rifle standards and he was having some consistent vertical issues. I noticed that he was not shouldering the rifle and advised him that because of the toe angle and probably inconsistencies in how the rifle recoiled from shot to shot that he probably would get better results if he held and shouldered the rifle. It worked. I learned this from a friend who shoots a schutzen rifle with a similar toe angle. Shooters who shoot free recoil tend to pay a lot of attention to things that affect how a rifle slides on the bags. If the rifle didn't move until the bullet was clear of the muzzle, then that should not matter. When shooters are not constrained by the rules they generally choose to have a flat butt angle for rifles that will be shot free recoil. I think that this is based on experience. In my experience, studies may or may not be conducted in a manner that yields results that are consistent with real world data. When there is a conflict, I do not automatically assume that the study is right and experience is incorrect.[/QUOTE]

Jr. High School Science. For every action there is a reaction. Recoil has to start as soon as the bullet moves. Interesting he mentions studies prove it. Fake news, the recoil starts after the bullet has left the rifle.

 

[Webster]

First, when the bullet moves faster then there is greater recoil energy and rifle recoil velocity increases which would cause the barrel to move at your hypothetical angle faster. In other words, the ratio of barrel angle to bullet velocity would stay pretty much the same but it would simply happen faster. This means that the effect on the point of impact wouldn't change with changes in powder charge weights.

Second, if this theory were true then accuracy shooting would be impossible because we'd have to know the exact muzzle velocity before we shot in order to know how to adjust our sights in order to impact the same spot all the time.

Finally, no firearm recoils to any substantial amount until the bullet leaves the muzzle so any firearm movement isn't caused by the bullet until the bullet exits the bore. Most rifle bullets leave the muzzle somewhere around 1 ms after the powder charge ignites and studies show that recoil movement doesn't usually happen until around 10 ms which means that the rifle starts to move when the bullet is about 2.8 feet beyond the muzzle (assuming a muzzle velocity of 2,800 fps).

Recoil after the bullet leaves the muzzle. It's all nonsense. So increasing powder won't produce a ladder test.

 

[Bart B.]

A website has a calculator you can put in the barrel profile dimensions plus the distance from its recoil axis to the rifle's center of mass below it and the rifle weight. Cartridge is a 308 Win.

http://www.geoffrey-kolbe.com/articles/rimfire_accuracy/barrel_vibrations.htm

A plot of the bore axis angle is graphed with barrel times shown. Use a 1.1 millisecond for a 22" barrel time to see the bore angle crossing point when it leaves.

Usually best to have bullets leaving on the muzzle axis upswing.