Load evaluation

[Natty Bumpo]

Like a lot of guys here, I evaluate my hand loads with a chronograph and by looking at the targets. On the target, I measure the extreme spread: the max. distance between the centers of the 2 outermost shots. I do this because it's the easiest way.

I realize there are more effective ways to evaluate loads, like average radius or radial standard deviation, that give a better picture of how a given load shoots. But calculating them is too tedius.

On one of the threads here I linked to another website that had some good articles on how best to measure shooting precision; written by John Leslie III. He references a program he wrote called ScorStat that can do the calculations. Problem is, this was written in 1993. I can't find anything on-line about ScorStat as it relates to our field.

I don't have a scanner and don't want to have to scan targets. What would be ideal, would be to have a target with background grid. On returning from the range, you could pinpoint your shots on the same target grid, and with a click of the mouse put a dot on the grid equal to your caliber. Press "enter" and it gives you the measurement you're looking for.

Does anyone know if there is such a thing?

 

[boomtube]

"I realize there are more effective ways to evaluate loads, like average radius or radial standard deviation, that give a better picture of how a given load shoots. But calculating them is too tedius."

I reject that as college classroom mental gamesmanship without merit. All that really counts in the field is, how often can I hit what I aim at? That's dependant on group size.

Average groups, radial SD, etc, doesn't mean a thing in the field. It's all limited to what I can hit, time after time. Maximum spread, of all shots, determines what I can count on hitting, not math games. Reduce maximum grouping and all the other factors will get better too! Keep it simple!

 

[AJ Peacock]

When I evaluate a load, I try to evaluate the load and not MY capabilities that day. My biggest challenge is judging the wind. All of my 'serious' rifles will shoot 1/2MOA or better. I on the other hand have my good days and my not so good days . So to better evaluate loads, I do the following.

I always shoot over a chronograph (when it's not raining etc.). And I only really pay attention to the vertical dispersion of the groups. I know that MY weakness (as the nut behind the trigger) is horizontal spread. So I don't pay too much attention to the wind when I'm comparing loads. I try to really focus on making the same shot every time and if the wind blows a bullet 1/2" to the left or right, I ignore it.

I then look only at the vertical dispersion and velocity spreads when I compare loads, because I know that my rifles all shoot nice small evenly distributed groups when the conditions are right.

I'm sure there are tons of reasons that I shouldn't ignore the horizontal spread, but it sure seems to work for me, since it seems like where I shoot, the wind is always switching from 8mph from the left to 8mph to the right etc.

Here is a picture of a spreadsheet view of how I evaluate loads (kind of a ladder / OCW type effort). I'm really looking for nodes here, by evaluating 3 consecutive shots with 3 consecutive loadings, but I shoot and evaluate groups the same way.

I hope this message wasn't too far off topic.

AJ

 

[Natty Bumpo]

I reject that as college classroom mental gamesmanship without merit. All that really counts in the field is, how often can I hit what I aim at? That's dependant on group size.

Average groups, radial SD, etc, doesn't mean a thing in the field. It's all limited to what I can hit, time after time. Maximum spread, of all shots, determines what I can count on hitting, not math games.

If I take 2 shots on paper and measure the distance between centers, I'm judging that load based on just 2 shots. If I take 20 shots on paper and measure the distance between the 2 most extreme shots, how many shots am I using to judge that load? Answer: 2. I don't regard finding a method that uses every shot to judge a load classroom mental gamesmanship.

I still use extreme spread because it's fast, easy, and I don't have any better alternatives. It works, but I'd like to find an easy way to do something better (in my opinion). When working up loads, I'm not trying to judge how well I can hit what I'm aiming at; I'm trying to judge how precise a given load works in my rifle.

 

[boomtube]

"I don't regard finding a method that uses every shot to judge a load classroom mental gamesmanship."

You sorta make my point when you say to use every shot. I said to make hits "everytime", and that includes as many shots as are fired with that load.

Obviously, the more rounds (samples) included, the more valid the information becomes. Using "average group size" to indicate the accuracy of a load is self delusional because a few rare small groups tend to "improve" the typical groups. On the other hand, a few large groups indicate the actual (repeatable) group size quite well.

Real accuracy, field accuracy, includes those stray rounds many call "flyers" and wish to cut off their wallet groups as if they didn't happen. But, we MUST include those flyers as an intregal part of the accuracy of the load if we wish to be honest with outselves.

Statistical analysis may help develop a better load but I can't see that it's any more useful than a simple measurement of the extreme spread.