So whats the real deal with all this ES/SD BS

[mikeeg02]

In a perfect world, es of 0 would shoot 1 hole groups at any distance. We dont live in a perfect world.

I dont bother to load perfectly consistent velocity ammo. But I do bother to load as consistent ammo as I can. I dont care how fast or slow or what its spread is going. I care about what it prints on paper. Some friends have chronographed my loads. And some were not tight es and some were close. Both want to print 3" for ten shots at a 1k. And one did. (Had to get someone else to pull the trigger but that's another subject lol) the load that shot 3", when he chronographed it, it had a 24fps es or something very close to that.

Ultimately we are trying to find a load that can tolerate all of OUR hand loading inconsistencies combined, and variances in bullets etc, and stay together as close as they can be. Not to mention were also trying to control small explosions as close as we can. Two bullets that reach the same velocity 15' from the barrel (or at the muzzle for that matter) may not of accelerated at the same rate to get there.

I think if you wanted to find a load strictly on velocity numbers, you would have to track its acceleration/deceleration between a couple points. This would require bullets with perfectly matched bc values, as bullet velocity, bc, and differential winds affect bullet flight/velocity.

 

[dkhunt14]

before you start flaming me Look back through my past posts, I have always stated that the person pulling the trigger more than the ammo he/she is using but threads like this confuse me. So work with me a bit, that is why I read the forum and ask questions.

Either consistent performing ammo matters or it doesn't which is it? Even though I have never set any sort of record and probably never will I will continue to go for the consistency simply becasue I enjoy the prep and reloading process and hopefully one day the wind/mirage reading might click for me. I am serious though, if you don't feel the velocity consistency matter, why do you bother? I am not trying to make anyone mad I am just curious. What matters and what doesn't, I seem to be getting mixed messages here

The point of my post was not about reloading good ammo. I can guarantee mine is loaded to a hundredth in powder. Even though I know I will get flamed, the primers are also within .01. The point of the post was that there are nodes, sometimes big, and chrono info isn't the most important thing for groups.

I had a Dasher that would shoot in the zeros at 100. The ES was never more then 2 or three. When I shot it in a 1000 yard match, the vertical was never less then 10 inches and most times 13 to 16. I wasted half a season trying to get that load to shoot because according to the numbers, it should have had very little vertical. After I changed loads and the ES was around 12 to 15, the gun shot good enough to win. Matt

 

[JimSC]

I had a Dasher that would shoot in the zeros at 100. The ES was never more then 2 or three. When I shot it in a 1000 yard match, the vertical was never less then 10 inches and most times 13 to 16. I wasted half a season trying to get that load to shoot because according to the numbers, it should have had very little vertical. After I changed loads and the ES was around 12 to 15, the gun shot good enough to win. Matt

interesting. I am an retired techie so the technical aspect of the sport fascinates me to no end. BTW an ES of 12 is pretty low for me. I try and get below 20 ES and 10 SD but I don't think I have ever managed single digits on the ES.

 

[Bart B.]

Does Sierra's program take barrel compensation into play? Matt

No, not directly. If the range step increment is set to a few yards and one bullet uses two muzzle velocities for a longer range, the trajectory height difference at 5 yards can be converted to MOA. If .05" above the LOS, that's darned close to the 1 MOA increase in bore axis angle at the muzzle needed to compensate for its slower muzzle velocity. Sierra's Infinity software calculates to two decimal places; nice for fine ballistic details.

 

[Bart B.]

I believe nodes and barrel compensation can change things. It doesn't make sense if looking at ballistic tables and numbers, but I have seen this happen many times.

Barrel compensation to make slower bullets leave at higher angles has been known and studied since the early 1900's. Barrel tuning weights tune the muzzle axis vibration frequencies to change the angle above LOS bullets leave at. On the upswing near the peak is the best place. Both center and rim fire rifles have them.

 

[tom]

I have no clue as to why your results came out the way they did but why do you bother handloading if you believe consistency or lack of consistency has no effect ? I thought that making consistent ammo is the entire goal of handloading, otherwise you might as well go buy white box ammo from Walmart

The results came out that way because the second two charges are in a node, and the first charge was under the node. I'm pretty sure Matt would then recommend loading as perfect of ammo as possible, and in the middle of the node as found in his "ladder TEST" he's giving in this example.

Tom

 

[INTJ]

There is still more about long range that we don’t know—especially BR—than we do know. The one thing I know for certainty is that best results are obtained when we try to make everything as good as possible, even if someone else thinks we are “over doing” things

If you are able to tune at the distance you compete, then a chrono my be of little benefit. If you have to tune at short range, and compete at long range, a chrono is a very useful tool.

As a rule of thumb when tuning at 100-200 yds, ES inside of 20 fps will not likely matter at 600/1000 yds. However, it is entirely possible that a great looking 100/200 yd group could have an ES of 30-35 fps, and that much ES may very well show up at 600/1000.

So, for those who compete against me and have to tune at short range, I STRONGLY discourage the use of a chronograph......

 

[Ccrider]

On the upswing near the peak is the best place.

I read somewhere that the node/tune that shifts the poi low was the best. Is that incorrect?

 

[Bart B.]

I read somewhere that the node/tune that shifts the poi low was the best. Is that incorrect?

Node/tune that shifts "point of impact" low on target?

Or lower on something else?

Sorry, I don't understand.

 

[Ccrider]

Node/tune that shifts "point of impact" low on target?

Or lower on something else?

Sorry, I don't understand.

The barrel whips up and then goes down and whips back up. The node was described as the time period in the harmonics where the barrel is at the top. or bottom of the whip. When at the top, the poi will be up on the target. As the barrel whips back down to the bottom the poi will be lower on the target.

The powder charge, seating depth and neck tension effect where the bullet is in the barrel vibration cycle when it leave the barrel.

 

[CharlieNC]

For differences in velocity a ballistic calculator gives the impact on vertical assuming there are no barrel harmonics, faster hits higher in a near perfect linear response. Increasing charge and velocity hits lower to form a node due to barrel harmonics. Couple the harmonic target response with a ballistic calculator and you can better predict nodes at different distances.

 

[Bart B.]

Ccrider, thanks for clarifying.

The best place for all bullets to leave is on the upswing. Slower bullets have to leave at higher angles to the LOS than faster ones to strike the same place on target.

The frequency the muzzle axis vibrates at is fixed. Where bullets leave is determined by muzzle velocity and barrel time. If bullets leave centered about the top antinode of the barrel whip, the slower half will leave on the down swing at the same angles as the faster ones. The reverse if bullets leave about the bottom antinode.

In vibrating things, a "node" refers to midpoint between extremes. "Antinodes" are the extreme points.

Have you ever seen Varmint Al Harral's or Geoffrey Kolbe's website pages on barrel whip compensation?