This velocity is impossible isn't it? I'm at a loss.

[kmartel]

That's gotta be it! Everyone else is wrong 'cause some jabroney paintballer had an epiphany and thinks there's nothing to the proven science of precision shooting. Build a 12lb trigger, hold your breath, line up the ol' tasco and let er rip! My guess is sub "minute of schoolbus" at least!
Hair on ya for trying to be different and rock the boat guy... But leave the man-bear-pig arguements out of the spotlight or everyone will just assume you have the IQ of a bag of skittles. Happy new year!

 

[prosper]

mmmhhmmmm. This is part of the reason why trying to compare POI's from different bullets and loads is ridiculous. Different weight bullets will cause different amounts of recoil and momentum. Different burn rates of powders will cause the acceleration of the bullet to be different. Different bullet profiles and bearing surfaces will affect your powder burn rate. All of this affects how much the barrel 'whips' and moves, and it means that the 'nodes' for different loads will behave entirely differently. Whether or not they're both 'at the top of the node' is utterly meaningless if the wave going down the barrel is of a different frequency, or amplitude.

Nevertheless, you don't have to UNDERSTAND why the POI is different between different loads, to know that it IS. Get enough experience shooting, and make enough first hand observations yourself, and forget about all this online ballistic theoretical masturbation

 

[DOUGLAS D]

delete

 

[fuzzynuts54]

Good stuff, you didnt pay attention obviously.

When the bullet is accelerating it causes a "ripple", "whip" or wobble in the barrel. For exactly the reason you have stated above. The point that the bullet exits the barrel, this wobble may be higher or lower than actual POA, hell it may be to the side and a minor deflection of the barrel could equal several inches down range.

SO!!! depending on charge weight, bullet velocity, bullet weight, etc. etc etc... Different loads will exit the barrel at different times relative to the "whip" of the barrel and have a different POI. This is the whole basis of load tuning and why dedicated target shooters us a heavy barrel design. The thicker the barrel the more the "whip" is reduced and load tuning becomes easier. It is also refered to as barrel harmonics, perhaps you have heard of the term?


Now, as you also stated in a previous post about trigger weight. Here is how that works. The more you interact with the firearm the more you are upsetting it, the whole idea behind a light trigger is that the rifle is not upset as much by the shooter. Try a tight grip for a 5 shot group, then try a very loose relaxed grip. You WILL see a different in POI. Try a 5 shot group holding your breath and try one shooting on the bottom of your breathing cycle when your lungs are empty. You may not even be aware of all the small parts of your interactions with the rifle that can seriously upset it. These things are generally what attributes to horizontal stringing on groups, and to be honest what every shooter is training to become consistant with so they shoot better. You have a point with your ideas on the rest attributing to POI changes but I can promise you it has more to do with your technique than the rest. The boys who do this for a living can shoot from an unsupported sitting position better than guys like us from a sandbad rest. Its all about training and technique, be consistant and the rest you use makes very little difference.


Perhaps you could stop being defensive and attacking people when they try to help or dish out advice. Of course this is probably all of our faults for not understanding what you are trying to say.

well now we're a little closer on the same path. I do have a heavy barrel, I do have a finely tuned trigger, I have a heavy rifle filled with bondo and shaped specifically to fit my face and my hands.

I do shoot quite well because I am well aware of the importants of minimizing putting undue amouts of force, unnatural torque and so on into my rifle. I didn't ask why a light trigger is imprtant because I don't know. It was for some narrow minded people could think back to basic shooting skills and think about why a natural and consistent recoil is important for accurate shooting because just as you said how important technique is.

If it were only as simple as having the cross hairs on target when the rigger breaks, technique would be meaningless would it not? But it's not that simple. We need the rifle to recoil in a consistent manner, in a consistent direction and this is why the same rifle may have a different poi with different people pulling the trigger.

As you mention the barrel begins it's whip the instant the bullet begins it's forward motion. Yes I know it does and I'm not discouting that fact at all. My point being that that whip can shift the poi by a few moa, but you can't see the muzzle move with your eyes can you? The angular movement is so miniscule that you telling me to watch a video is going to prove what? If the video proves anything it would prove there is no such thing as barrel harmonics which we know is untrue.

The facts of the matter is that the instant the bullet begins it's movment down the barrel, the barrel begins to whip. It also imparts a opposite force we call recoil. The shooter (and resting surface) are directly in control of what directions the rifle moves and this is why a light trigger reduces one of the unnatural forces. This is why a natural point of aim is important because pushing your rifle sidways or torquing it imparts another unnatural force.
Anything unnatural is inconsistent, uncontrolable, unrepeatable, and unpredictable. This is why consistent shooting form is important. If it were only as simple as lining up the sights none of this would mean anything and everyone on the earth would be a top notch shooter.

And why else is all that important? Well because all those Factor into where the muzzle is pointed the instant the bullet leaves, weather you can see it or not on film.

I'm not saying I expect my 150's and 208's to go in the same hole when I shoot off a sand bag. For all I really know they might even spread farther apart but what i am sure about is that these 2 different recoil charachteristics are causing 2 different amounts of muzzle jump off the bipod and muzzle jump DOES affect poi to SOME degree. Maybe it's almost unmeasurable, maybe it's a few moa. I'll find out tomorrow.

 

[CanuckWR]

well now we're a little closer on the same path. I do have a heavy barrel, I do have a finely tuned trigger, I have a heavy rifle filled with bondo and shaped specifically to fit my face and my hands.

I do shoot quite well because I am well aware of the importants of minimizing putting undue amouts of force, unnatural torque and so on into my rifle. I didn't ask why a light trigger is imprtant because I don't know. It was for some narrow minded people could think back to basic shooting skills and think about why a natural and consistent recoil is important for accurate shooting because just as you said how important technique is.

If it were only as simple as having the cross hairs on target when the rigger breaks, technique would be meaningless would it not? But it's not that simple. We need the rifle to recoil in a consistent manner, in a consistent direction and this is why the same rifle may have a different poi with different people pulling the trigger.

As you mention the barrel begins it's whip the instant the bullet begins it's forward motion. Yes I know it does and I'm not discouting that fact at all. My point being that that whip can shift the poi by a few moa, but you can't see the muzzle move with your eyes can you? The angular movement is so miniscule that you telling me to watch a video is going to prove what? If the video proves anything it would prove there is no such thing as barrel harmonics which we know is untrue.

The facts of the matter is that the instant the bullet begins it's movment down the barrel, the barrel begins to whip. It also imparts a opposite force we call recoil. The shooter (and resting surface) are directly in control of what directions the rifle moves and this is why a light trigger reduces one of the unnatural forces. This is why a natural point of aim is important because pushing your rifle sidways or torquing it imparts another unnatural force.
Anything unnatural is inconsistent, uncontrolable, unrepeatable, and unpredictable. This is why consistent shooting form is important. If it were only as simple as lining up the sights none of this would mean anything and everyone on the earth would be a top notch shooter.

And why else is all that important? Well because all those Factor into where the muzzle is pointed the instant the bullet leaves, weather you can see it or not on film.

I'm not saying I expect my 150's and 208's to go in the same hole when I shoot off a sand bag. For all I really know they might even spread farther apart but what i am sure about is that these 2 different recoil charachteristics are causing 2 different amounts of muzzle jump off the bipod and muzzle jump DOES affect poi to SOME degree. Maybe it's almost unmeasurable, maybe it's a few moa. I'll find out tomorrow.

Ok, we are on the same page.

My comment on the video was to demonstrate that when you register "felt" recoil and muzzle jump, the bullet is long gone. Any POI change from bipod to sandbag will almost certainly be from body position and virtually undetectable deflection of the legs of the bipod. My $.02 on that idea anyway.

 

[fuzzynuts54]

Well I made it out yesterday and the weather was decent. I chrono'ed both loads again and a factory load also. As before the 150gr smk with 77gr of imr4831 averages 3300 give or take. The 208amax with 79.5gr of h1000 is averaging 2880fps.
These cheap Winchester 180gr powerpoints are 2800 (they claim 2950) these pos factory junk actually shot better than I expected. Right in there with handloads. (I'm not sure how I feel about that)

anyways from bipod to bag.... Bipod was putting my 150smk's about 1" above the bull, 208's were about 2" below it. Switching to sand bags brought the 150's down to 3/4" and the 208's fell to 3-3/4" below. This is a 2.439moa spread opening to a 3.455 moa spread. Meaning the bipod caused a less than 1/4moa change in the smk's poi but about 1-1/4moa of the amax's.

While neither myself or my rifle are anthing that even resemble "precision", my groups aren't always (or even often) bug holes but I do feel my testing was accurate enough to come to a fairly certain conclusions that 2 different recoiling loads will not only have different poi's from each other but also their relation to eachother will change when shot from different rests. Now the hard part for me to admit is that switching from bipod to bag did change the loads poi relative to eachother as expected.... It was the opposite direction as I expected. I was expecting them to migrate closer, but instead it expanded about 1.2moa.

So I looked for a rifle recoil calculator and input the numbers. I was expecting to see the 150's leading somewhere in the result boxes but no, the 208's have higher recoil acceleration, energy, ect... But this is not what it feels like when I shoot. I wonder if the brake changes this? Is it possible there is so much more gas being directed rearward as te bullet exposes the ports to reduce recoil in a greater proportion than the quicker burning powder with the lighter bullet? As I ask myself this, I can imagine the slower burning, larger powder charge and the heavier bullet creating a larger volume/longer duration and higher velocity of gasses pulling the muzzle away from me... Hence what I percieve as a muted recoil. Hmmmm... Here I go again..

 

[gnosis]

Nodes, nodes, nobody nodes...

Delete.

 

[gnosis]

Nodes, nodes, nobody nodes...

I think you need to go to www.frfrogspad.com/loaddev.htm and read the node explanation completely. Once you have done that, re- read all other replies that pertain to nodes, and I think you will have a better idea where everyone was coming from.
While differing recoil factors play a part in changing poi, so does every position you shoot from, including going from a bipod position to a sandbag position.
Even pulling your head away momentarily in the middle of a shot string will not let you get it back EXACTLY where it was before you moved it, thus changing poi.
The point you were trying to prove is a valid one, but only a very small part of an enormous equation we call accuracy.
What you were calling the high point of the node is actually the bullet leaving the barrel with the greatest upward motion ( at the top of the barrel) the node is where the bullet exits at the moment of the least barrel movement therefore generating the tightest consistent groups.
There is alot to learn from the experience on this forum, try not to be defensive ( can be difficult) or beat a dead horse. If you are receiving the same message from many different people, maybe there is something there!
But above all DO keep questioning as there is still much yet to be discovered.

I'd say it's just my 2cents but that was more like 4bucks