recoil v accuracy

[WildRose]

Did you read the FEA analysis and shooting test I posted on VarmintAl's site ? It was proven both practically and analytically that by changing the powder load a tiny bit, or moving the tuning weight less than 1/2" forward or backwards that the muzzle could be pointing upward, straight or downward with no other contributing factors.

The only part of recoil which has any significance to point of impact is the part which occurs before the bullet leaves the barrel. What happens after the bullet leaves the barrel only serves to scare the shooter.

If one can't or won't read, can't comprehend the subject matter and can't or won't ask questions about things one does not understand, one will remain forever ignorant. Barrel Tuner Analysis -- FEA Dynamic Analysis of Esten's Rifle with/without a Tuner.

That is factually incorrect.

The buffeting that occurs just after the bullet exits the barral can dramatically affect accuracy which is why a bad crown, or improperly mounted muzzle brake can make an otherwise pefect rifle perfectly useless beyond 300yards.

Al's "barrel tuner" does one thing, it changes the harmonics of the barrel. It does nothing about recoil.

 

[WildRose]

The only thing you have proven is that you are a BS artist who likes to use words you don't know the meaning of and make up preposterous statements that negate the known laws of physics.

What you have poven is that you are an arrogant snot incapable of intelligent discourse much less learning anything from those with decades more experience doing this quite successfully.

Go bully someone else. It won't work on me.

 

[bigngreen]

Finally found the video I was looking for! Please notice the recoil without any bullet exiting the barrel on the ones that don't blow, or am I not seeing recoil?

YouTube - ‪Rifle burst test - Remington, Browning, Sako, Blaser, Mannlicher, Antonio Zoli, Howa, Tikka‬‏

 

[WildRose]

Finally found the video I was looking for! Please notice the recoil without any bullet exiting the barrel on the ones that don't blow.

YouTube - ‪Rifle burst test - Remington, Browning, Sako, Blaser, Mannlicher, Antonio Zoli, Howa, Tikka‬‏

Umm THat's a rifle expoloding. The barrel is expanding behind the vise as pressure builds forcing the rifle backwards, that is going to greatly increase the observable rearward motion.


You'll also note that what recoil effect there is, is propelling the rifle pretty much straight backward until it explodes.

 

[bigngreen]

Did you even hit play? The recoil stops as soon and the gasses are vented on the ones that blow, the ones that don't continue to recoil don't they.

 

[WildRose]

I did not read the entire thread as it got old after 3 pages. Did anyone ever mention the shifting of the center of gravity that occurs during recoil. The reason some recoil calculators ask for weight of powder charge as well as bullet. Those two masses shift the center of gravity of the rifle the instant the bullet starts to move causing the rifle to move. I'm no physicist but I have heard that people over emphasize the rocket effect and ignore the shift in the center of gravity.

Ok let's look at the change in center of gravity.

We have a projectile that starts of about 1/4 of the length (from the rear) of the total rifle butt to end of bore, that who's mass is going to be something less than 1/277 of the rifle.

Now typically we mount our bipods, or set the rifle on whatever rest we are using about 1/4-1/3 of the total length of the rifle back from the end of the bore.

This shifting of center of mass is going to affect accuracy to what degree considering the bullet will be out of the end of the barrel in around .00133 seconds.

How is that going to affect accuracy in light of all of the other forces acting on the rifle?

 

[WildRose]

Did you even hit play? The recoil stops as soon and the gasses are vented on the ones that blow, the ones that don't continue to recoil don't they.

Yes, so as far as affecting accuracy how is this going to do so?

The motion is linear and of course there is no mass of a shooter behind the butt to limit the movement of the rifle.

Looking at it again, we also don't know how much of that observed rearward motion is due to them jerking the rope to pill the trigger or how much force was being exerted by the vise on the barrel which would matter a great deal.

 

[bigngreen]

It means there is recoil happening with the bullet in the barrel so recoil and our interaction with it can effect accuracy and POI. Does it not?

 

[WildRose]

It means there is recoil happening with the bullet in the barrel

We have all acknowledged this fact.

so recoil and our interaction with it can effect accuracy and POI. Does it not?

How much can we interact with a force that is coming straight back during the .00133 seconds the round is still in the barrel in such a way as to interfere with accuracy?

Remember the bulk of this force is being directed straight back at the shooter in line with the target during this time. Not up and down, and not left to right.

Figuring we have a maximum recoil force of 20mph that is 1.446 feet per second.

This means that at most the recoil force can move the rifle 1.446 x .00133=.001923 Ft during the length of time between ignition and exit from the barrel or just .000160 inches in any direction and again, the bulk of that forces is directly in line between the POI and shooter.

 

[WildRose]

Look at this video. It shows several good slow motion cycles of Tac .50 firing.

Look at just how little recoil movement there is before the round exits.

[ame=http://www.youtube.com/watch?v=_MK4SEoBFXk&feature=player_detailpage]YouTube - ‪Longest Sniper Kill Ever 1.5 Miles‬‏[/ame]

 

[WildRose]

This site offers a pretty hand recoil calculator for those that want to play with their loads/rifles for comparison.

Recoil Calculator

 

[WildRose]

Originally Posted by lightwind
WildRose: Please excuse my nit-picking but I am still not completely understanding a couple of your answers. Some of them are very close to my view and I am ready to agree to some of those. However, there are still some issues you brought up I don't fully understand.

A) You said (on page 13): "Incorrect, pressure continues to build as long as it is constrained by the bullett and it is still burning."

What I interpret "pressure continues to build" to mean is a monotonically increasing curve of pressure.

Your interpretation, not my intent.

As the volume increases the pressure drops from the initial. However. With a faster burning powder, combustion is completed very quickly. That is why we use the faster burning powders with lower volume cases, and shorter bbls with the fastest burning powders typically being used in pistol cartridges.

With our larger caliber, higher capacity cases and heavier projectiles we utilize slower burning powders in order to spread out the total time pressue is being created through combustion.

If all the powder is consumed inside the case/chamber, your highest velocity potential comes when the bullet separates from the case.

What we do instead with the slower burning powders and longer barrels is to continue combustion throughout the length of the barrel, so that while the pressure gradient falls as the case/bullet separates, we have a longer burn time allowing for more total velocity.

Same exact load fired in shorter vs longer barrels provides consistenly higher velocities for that reason. You have a longer time for burn and thus increased velocity.

No you continue producing pressure, but the peak pressure is reached in the first milisecond. Pressure begins to drop as the volume increases, but it continues pushing longer, and producing ever greater velocity the longer that pressure is constrained in the pressure vessel of the chamber and bore. Longer burn time, more total volume of gas produced, more total velocity with lower pressures than would be produced by a faster burning powder.


The pressure peak, is not the end of pressure being produced.
The bullet cannot accelerate faster than the gas behind it expands. When the pressure peaks, if combustion does not contine as the volume of the cylinder increases, velosity would necessarily be retarded and the friction produced between the bullet and lans/grooves would quickly decelerate it.

We are not acting in the absence of friction here and by necessity the friction is considerable in order to achieve the desired pressures for acceleration.

Only through the continued release of those hot gases produced by the combustion, can the projectile contine to gain speed rather than lose it.

One of the best reads ever on the subject.

Hornady 99238 Handbook of Cartridge Reloading 8th Edition#

Of course I'm still working off of the 2nd edition.

Light Wind, I found this page on internal ballistics that explains much better than I did/can as to why we use slower burning powders as we increase diameter of bore, mass of projectile and length of barrel.

Internal Ballistics

As you see using the slower burning powders moves the peak of the pressure curve forward as well as flattening it vs using the faster burning powders for these loads.

 

[Greyfox]

It means there is recoil happening with the bullet in the barrel so recoil and our interaction with it can effect accuracy and POI. Does it not?

I believe this statement to be true.

I was in a long range match a couple of years ago shooting my 7mm-08, with a bipod. At my home range before the match it wa dead on shooting .5moa or less. When I went to the sighter board at the match, I couldn't keep my groups under 1 MOA. I couldn't figure out what was going on...thought maybe the scope went bad, fouling ,me,etc. A guy came over and handed me a sheet of plexiglas to put under my bipod legs and I instantly Restored my original accuracy. My practice range bench had a smooth wood surface so during primary recoil the rifle came straight back not effecting my accuracy. The bench top at the match had a carpet on it that had a course weave base. This caused the bipod legs to not come back smoothly effecting the accuracy on primary recoil. The guys at the club said they have seen this happen on numerous occasions. The difference wasn't that big, but I would have had no chance of winning this match with a 1moa rifle. It was a 200 yard egg shoot. A week later I confirmed this effect at my home range with a price of carpet.

Actual results trumps theory every time!

 

[Boss Hoss]

I believe this statement to be true.

I was in a long range match a couple of years ago shooting my 7mm-08, with a bipod. At my home range before the match it wa dead on shooting .5moa or less. When I went to the sighter board at the match, I couldn't keep my groups under 1 MOA. I couldn't figure out what was going on...thought maybe the scope went bad, fouling ,me,etc. A guy came over and handed me a sheet of plexiglas to put under my bipod legs and I instantly Restored my original accuracy. My practice range bench had a smooth wood surface so during primary recoil the rifle came straight back not effecting my accuracy. The bench top at the match had a carpet on it that had a course weave base. This caused the bipod legs to not come back smoothly effecting the accuracy on primary recoil. The guys at the club said they have seen this happen on numerous occasions. The difference wasn't that big, but I would have had no chance of winning this match with a 1moa rifle. It was a 200 yard egg shoot. A week later I confirmed this effect at my home range with a price of carpet.

Actual results trumps theory every time!

This is one reason before a match relay or just shooting my hunting rifles ALWAYS spend considerable time making sure the rifle is level and that rest and bags are perfectly settled. The rifle should recoil straight back as much as possible with as little jump at the muzzle as possible.